Exchange Online Limits

Find the Exchange Online limits for a variety of service areas, including address book limits, mailbox storage limits, and reporting and message trace limits, to name just a few.

Note

If you need assistance with a task or if you are troubleshooting a problem, you might find the following articles helpful:
Email (for help creating and sending email)
Email in Office 365 for business - Admin Help
Fix Outlook and Office 365 problems with Microsoft Support and Recovery Assistant for Office 365
Email non-delivery reports in Office 365
Exchange Online Help

The limits in Microsoft Exchange Online fit into one of the following categories:

Important

• The limits applied to a Microsoft Office 365 organization may differ depending on how long the organization has been enrolled in the service.
• When a limit is changed in the Microsoft data centers, it can take some time to apply the change to all existing customers.
• You can't modify most of these limits, but you and your users should be aware of them.
• These limits apply to both internal and external recipients.
• By default, Exchange Online Protection (EOP) protects Exchange Online mailboxes. For limits that apply to EOP features in Exchange Online, see Exchange Online Protection Limits.
• For information about Office 365 group limits, see "How do I manage my groups?" in Learn about Office 365 groups.

Address book limits

  • Address list limit The maximum number of address lists that can be created in an Exchange Online or Exchange Server 2013 organization. This number includes the default address lists in Exchange Online, such as All Contacts and All Groups.

    Note

    A maximum of 20 address lists can be assigned to a single offline address book (OAB).

  • Offline address book limit The maximum number of offline address books (OAB) that can be created in an Exchange Online or Exchange Server 2013 organization.

  • Address book policies limit The maximum number of address book policies (ABP) that be created in an Exchange Online or Exchange Server 2013 organization.

  • Global address lists The maximum number of global address lists (GAL) that be created in an Exchange Online or Exchange Server 2013 organization.

Address book limits across Office 365 options

Feature
Office 365 Business Essentials
Office 365 Business Premium
Office 365 Enterprise E1
Office 365 Enterprise E3
Office 365 Enterprise E5
Office 365 Enterprise F1
Address list limit
1000
1000
1000
1000
1000
1000
Offline address book (OAB) limit
250
250
250
250
250
250
Address book policies (ABP) limit
250
250
250
250
250
250
Global address lists limit
250
250
250
250
250
250

Address book limits across standalone plans

Feature
Exchange Server 2013
Exchange Online Plan 1
Exchange Online Plan 2
Exchange Online Kiosk
Address list limit
1000
1000
1000
1000
Offline address book (OAB) limit
250
250
250
250
Address book policies (ABP) limit
250
250
250
250
Global address lists limit
250
250
250
250

Mailbox storage limits

The amount of mailbox storage available is determined by the mailbox type and the user's subscription license. Administrators can reduce maximum mailbox sizes per user or globally.

Note

Using journaling, transport rules, or auto-forwarding rules to copy messages to an Exchange Online mailbox for the purposes of archiving is not permitted. A user's archive mailbox is intended for just that user. Microsoft reserves the right to deny unlimited archiving in instances where a user's archive mailbox is used to store archive data for other users.

Storage limits across Office 365 options

Feature
Office 365 Business Essentials
Office 365 Business Premium
Office 365 Enterprise E1
Office 365 Enterprise E3
Office 365 Enterprise E5
Office 365 Enterprise F1
User mailboxes
50 GB
50 GB
50 GB
100 GB
100 GB
2 GB
Archive mailboxes7, 8
50 GB
50 GB
50 GB
Unlimited1
Unlimited1
Not available4
Shared mailboxes
50 GB2
50 GB2
50 GB2
50 GB2,9
50 GB2,9
50 GB2
Resource mailboxes
50 GB3
50 GB3
50 GB3
50 GB3,9
50 GB3,9
50 GB3
Site mailboxes5
50 GB
50 GB
50 GB
50 GB
50 GB
Not available
Public folder mailboxes
50 GB6
50 GB6
50 GB6
100 GB6
100 GB6
Not available
Group mailboxes
50 GB
50 GB
50 GB
50 GB
50 GB
50 GB

Note

1 Each user initially receives 100 GB of storage in the archive mailbox. When auto-expanding archiving is turned on, additional storage is automatically added when the 100 GB storage capacity is reached. For more information, see Overview of unlimited archiving in Office 365. See the Office 365 Roadmap for details about availability.
2 To access a shared mailbox, a user must have an Exchange Online license. Shared mailboxes don't require a separate license. However, without a license, shared mailboxes are limited to 50 GB. To increase the mailbox size, an E3 or E5 license must be assigned. This will increase the mailbox to 100 GB. If you want to enable the archive mailbox or put a Litigation Hold on a shared mailbox, then an Exchange Online Plan 2 license or an Exchange Online Plan 1 with Exchange Online Archiving license is required. If you enable the archive mailbox and auto-expanding archiving for a shared mailbox, additional storage is automatically added when the 100 GB storage capacity for the archive mailbox is reached.
3 Resource mailboxes don't require a license. However, without a license, shared mailboxes are limited to 50 GB. To increase the mailbox size, an E3 or E5 license must be assigned. This will increase the mailbox to 100 GB.
4 Archive mailboxes aren't included in Exchange Online Kiosk. However, they can be purchased as an add-on through Exchange Online Archiving. For more information, please see the Exchange Online Archiving Service Description.
5 Site mailboxes are created and managed in SharePoint Online. For more information, see Prepare for using site mailboxes in Office 365.
6 You are limited to 1,000 public folder mailboxes, and the maximum total size of all public folder mailboxes is 50 TB. Hierarchy Serving mailboxes are limited to 100 public folder mailboxes.
7 Archive mailboxes can only be used to archive mail for a single user or entity (such as a shared mailbox) for which a license has been applied. Using archive mailboxes as a means of storing mail from multiple users or entities is prohibited. For example, an IT administrator can't create a shared mailbox and have users copy it (through the Cc or Bcc field, or through a transport rule) for the explicit purpose of archiving. Note that a shared mailbox that multiple people use does not actually store email for those individual users. Multiple users have access, and they send email as the shared mailbox. Therefore, the only emails stored in the shared mailbox are those sent to or from it, as the shared mailbox.
8 If you have created a retention policy in Exchange Online, messages will be automatically moved to a user's archive mailbox only if the user's primary mailbox is larger than 10 MB. The retention policy will not run automatically for mailboxes that are smaller than 10 MB.
9 Shared and resource mailboxes don't require a license. However, without a license, shared mailboxes are limited to 50 GB. To increase the mailbox size, an E3 or E5 license must be assigned. This will increase the mailbox to 100 GB.

Storage limits across standalone plans

Feature
Exchange Server 2013
Exchange Online Plan 1
Exchange Online Plan 2
Exchange Online Kiosk
User mailboxes
2 GB1
50 GB
100 GB
2 GB
Archive mailboxes8, 9
100 GB1
50 GB
Unlimited2
Not available5
Shared mailboxes
2 GB1
50 GB3
50 GB3,10
50 GB3
Resource mailboxes
2 GB1
50 GB4
50 GB4,10
50 GB4
Public folder mailboxes
2 GB6
50 GB7
100 GB7
Not available
Group mailboxes
50 GB
50 GB
50 GB
50 GB

Note

1 This is the default mailbox size for Exchange Server 2013 organizations. Administrators can change this value for their organization. There isn't a maximum storage limit for on-premises mailboxes.
2 Each user initially receives 100 GB of storage in the archive mailbox. When auto-expanding archiving is turned on, additional storage is automatically added when the 100 GB storage capacity is reached. For more information, see Overview of unlimited archiving in Office 365. See the Office 365 Roadmap for details about availability for auto-expanding archiving.
3 To access a shared mailbox, a user must have an Exchange Online license. Shared mailboxes don't require a separate license. However, without a license, shared mailboxes are limited to 50 GB. To increase the mailbox size, an Exchange Online Plan 2 license must be assigned. This will increase the mailbox to 100 GB. If you want to enable the archive mailbox or put a Litigation Hold on a shared mailbox, then an Exchange Online Plan 2 license or an Exchange Online Plan 1 with Exchange Online Archiving license is required. If you enable the archive mailbox and auto-expanding archiving for a shared mailbox, additional storage is automatically added when the 100 GB storage capacity for the archive mailbox is reached.
4 Resource mailboxes don't require a license. However, without a license, shared mailboxes are limited to 50 GB. To increase the mailbox size, an Exchange Online Plan 2 license must be assigned. This will increase the mailbox to 100 GB.
5 Archive mailboxes aren't included in Exchange Online Kiosk. However, they can be purchased as an add-on through Exchange Online Archiving. For more information, please see the Exchange Online Archiving Service Description.
6 This is the default mailbox size for Microsoft Exchange Server 2013 organizations. Administrators can change this value for their organization. In Exchange Server 2013, you are limited to 100 public folder mailboxes, and the maximum total size of all public folder mailboxes is 50 TB.
7 In Exchange Online, you are limited to 1,000 public folder mailboxes, and the maximum total size of all public folder mailboxes is 50 TB.
8 Archive mailboxes can only be used to archive mail for a single user or entity for which a license has been applied. Using an archive mailbox as a means to store mail from multiple users or entities is prohibited. For example, IT administrators can't create shared mailboxes and have users copy (through the Cc or Bcc field, or through a transport rule) a shared mailbox for the explicit purpose of archiving.
9 If you have created a retention policy in Exchange Online, messages will be automatically moved to a user's archive mailbox only if the user's primary mailbox is larger than 10 MB. The retention policy will not run automatically for mailboxes that are smaller than 10 MB.
10 Shared and resource mailboxes do not require a license to be assigned. However, without a license, these mailboxes are limited to 50 GB. To increase the mailbox size, an Exchange Online Plan 2 license must to be assigned. This will increase the mailbox to 100 GB.

Note

A shared mailbox is not designed for direct logon. The user account for the shared mailbox itself should stay in a Disabled (or "disconnected") state.

Capacity alerts

Exchange Online provides three kinds of notifications when a user's mailbox is nearing, or at, capacity:

  • Warning The user receives an email warning that the mailbox is approaching the maximum size limit. This warning is intended to encourage users to delete unwanted mail.

  • Prohibit Send The user receives a prohibit-send notification email when the mailbox size limit is reached. The user cannot send new messages until enough email is deleted to bring the mailbox below the size limit.

  • Prohibit Send/Receive Exchange Online rejects any incoming mail when the mailbox size limit is reached, and sends a non-delivery report (NDR) to the sender. The sender has the option to try resending the mail later. To receive messages again, the user must delete email until the mailbox is below the size limit.

Capacity alerts across Office 365 options

Feature
Office 365 Business Essentials
Office 365 Business Premium
Office 365 Enterprise E1
Office 365 Enterprise E3
Office 365 Enterprise E5
Office 365 Enterprise F1
Warning
49 GB
49 GB
49 GB
98 GB
98 GB
1.96 GB
Prohibit Send
49.5 GB
49.5 GB
49.5 GB
99 GB
99 GB
1.98 GB
Prohibit Send/Receive
50 GB
50 GB
50 GB
100 GB
100 GB
2 GB

Capacity alerts across standalone plans

Feature
Exchange Server 2013
Exchange Online Plan 1
Exchange Online Plan 2
Exchange Online Kiosk
Warning
1.9 GB1
49 GB
98 GB
1.96 GB
Prohibit Send
2 GB1
49.5 GB
99 GB
1.98 GB
Prohibit Send/Receive
2.3 GB1
50 GB
100 GB
2 GB

Note

1 This is the default value for Exchange Server 2013 organizations. Administrators can change this value for their organization.

Mailbox folder limits

These limits are intended to limit mailboxes to known dimensions that can be supported in Exchange Online. The goal of these limits is to prevent an infinite number of mailbox items per folder, an infinite number of folders per mailbox, or an infinite number of public folders per Exchange Online organization. For practical purposes, mailbox folder limits are in effect unlimited and sufficient to support most Exchange Online mailboxes and on-premises mailboxes that are migrated to Exchange Online.

  • Maximum number of messages per mailbox folder Specifies the maximum number of messages for a mailbox folder. New messages can't be delivered or saved in a folder when this limit is reached.

  • Warning for number of messages per mailbox folder Specifies the number of messages that a mailbox folder can hold before Exchange Online sends a warning message to the mailbox owner. When this quota is reached, warning messages are sent once a day.

  • Maximum number of messages per folder in the Recoverable Items folder Specifies the maximum number of messages that can be contained in each folder in the Recoverable Items folder. When a folder exceeds this limit, it can't store new messages. For example, if the Deletions folder in the Recoverable Items folder has exceeded the message count limit and the mailbox owner attempts to permanently delete items from their mailbox, the deletion will fail.

  • Warning for number of messages per folder in the Recoverable Items folder Specifies the number of messages that each folder in the Recoverable Items folder can hold before Exchange Online logs an event to the application event log.

  • Maximum number of subfolders per mailbox folder Specifies the maximum number of subfolders that can be created in a mailbox folder. The mailbox owner won't be able to create a new subfolder when this limit is reached.

  • Warning for number of subfolders per mailbox folder Specifies the number of subfolders that can be created in a mailbox folder before Exchange Online sends a warning message to the mailbox owner. When this quota is reached, warning messages are sent once a day.

  • Maximum folder hierarchy depth Specifies the maximum number of levels in the folder hierarchy of a mailbox. The mailbox owner won't be able to create another level in the folder hierarchy of the mailbox folder when this limit is reached.

  • Warning for folder hierarchy depth Specifies the number of levels in the folder hierarchy of a mailbox folder that can be created before Exchange Online sends a warning message to the mailbox owner. When this quota is reached, warning messages are sent once a day.

  • Maximum number of public folders Specifies the maximum number of public folders in the complete public folder hierarchy. When this limit is reached, existing public folders must be deleted before new public folders can be created.

  • Maximum number of subfolders per public folder Specifies the maximum number of subfolders that can be created in a public folder. New subfolders can't be created in a public folder when this limit is reached.

  • Warning for number of subfolders per public folder Specifies the number of subfolders that can be created in a public folder before Exchange Online sends a warning message to the folder owner. If no owner exists, warning messages are sent to users with Owner permissions. When this quota is reached, warning messages are sent once a day.

Mailbox folder limits across Office 365 options

Feature
Office 365 Business Essentials
Office 365 Business Premium
Office 365 Enterprise E1
Office 365 Enterprise E3
Office 365 Enterprise E5
Office 365 Enterprise F1
Maximum number of messages per mailbox folder
1 million
1 million
1 million
1 million
1 million
1 million
Warning for number of messages per mailbox folder
900,000
900,000
900,000
900,000
900,000
900,000
Maximum number of messages per folder in the Recoverable Items folder
3 million
3 million
3 million
3 million
3 million
3 million
Storage quota for Recoverable Items folder in primary mailbox (not on hold)
30 GB
30 GB
30 GB
30 GB
30 GB
30 GB
Storage quota for Recoverable Items folder in primary mailbox (on hold)
100 GB
100 GB
100 GB
100 GB
100 GB
100 GB
Storage quota for Recoverable Items folder in archive mailbox (not on hold)
30 GB
30 GB
30 GB
Unlimited2
Unlimited2
30 GB
Storage quota for Recoverable Items folder in archive mailbox (on hold)
100 GB1
100 GB1
100 GB1
Unlimited2
Unlimited2
100 GB1
Warning for number of messages per folder in the Recoverable Items folder
2.75 million
2.75 million
2.75 million
2.75 million
2.75 million
2.75 million
Maximum number of subfolders per mailbox folder
10,000
10,000
10,000
10,000
10,000
10,000
Warning for number of subfolders per mailbox folder
9000
9000
9000
9000
9000
9000
Maximum folder hierarchy depth
300
300
300
300
300
300
Warning for folder hierarchy depth
250
250
250
250
250
250
Maximum number of public folders
500,000
500,000
500,000
500,000
500,000
Not available
Maximum number of subfolders per public folder
10,000
10,000
10,000
10,000
10,000
Not available
Warning for number of subfolders per public folder
9000
9000
9000
9000
9000
Not available

Note

1 This is the storage quota for the Recoverable Items folder, not the quota for the entire archive mailbox. The storage quota for the archive mailbox is unlimited for users with an Exchange Online Plan 2 license or for users who have both an Exchange Online Plan 1 and an Exchange Online Archiving license. For information about increasing the Recoverable Items quota, see Increase the Recoverable Items quota for mailboxes on hold.
2 The initial storage quota for the Recoverable Items folder in an archive mailbox is 100 GB. When auto-expanding archiving is turned on, additional storage is automatically added when the storage capacity for the Recoverable Items folder is reached. For more information, see Overview of unlimited archiving in Office 365. See the Office 365 Roadmap for details about availability of auto-expanding archiving.

Mailbox folder limits across standalone plans

Feature
Exchange Server 2013
Exchange Online Plan 1
Exchange Online Plan 2
Exchange Online Kiosk
Maximum number of messages per mailbox folder
No limit1
1 million
1 million
1 million
Warning for number of messages per mailbox folder
No limit
900,000
900,000
900,000
Maximum number of messages per folder in the Recoverable Items folder
No limit
3 million
3 million
3 million
Storage quota for Recoverable Items folder in primary mailbox (not on hold)
30 GB
30 GB
30 GB
30 GB
Storage quota for Recoverable Items folder in primary mailbox (on hold)
100 GB
100 GB
100 GB
100 GB
Storage quota for Recoverable Items folder in archive mailbox (not on hold)
30 GB
30 GB
30 GB
30 GB
Storage quota for Recoverable Items folder in archive mailbox (on hold)
100 GB2
100 GB2
Unlimited3
Unlimited3
Warning for number of messages per folder in the Recoverable Items folder
No limit
2.75 million
2.75 million
2.75 million
Maximum number of subfolders per mailbox folder
No limit
1000
1000
1000
Warning for number of subfolders per mailbox folder
No limit
900
900
900
Maximum folder hierarchy depth
No limit
300
300
300
Warning for folder hierarchy depth
No limit
250
250
250
Maximum number of public folders
1,000,000
100,000
100,000
Not available
Maximum number of subfolders per public folder
N/A
1,000
1,000
Not available
Warning for number of subfolders per public folder
N/A
900
900
Not available

Note

1 Microsoft recommends no more than 1,000,000 messages per mailbox folder. >
2 This is the storage quota for the Recoverable Items folder, not the quota for the entire archive mailbox. The storage quota for the archive mailbox is unlimited for users with an Exchange Online Plan 2 license or for users who have both an Exchange Online Plan 1 and an Exchange Online Archiving license. For information about increasing the Recoverable Items quota, see Increase the Recoverable Items quota for mailboxes on hold.
3 The initial storage quota for the Recoverable Items folder in an archive mailbox is 100 GB. When auto-expanding archiving is turned on, additional storage is automatically added when the storage capacity for the Recoverable Items folder is reached. For more information, see Overview of unlimited archiving in Office 365. See the Office 365 Roadmap for details about availability of auto-expanding archiving.

Message limits

The following limits are applied to every email message.

  • Message size limit Message size limits are necessary to prevent large messages from blocking delivery of other messages and affecting service performance for all users. These limits include attachments, and apply organization-wide to all messages (inbound, outbound, and internal). Messages larger than this limit will not be delivered, and the sender will receive a non-delivery report (NDR). While message size limits can be configured up, down, or on a per-user basis, administrators can also create transport rules to limit the maximum size of any individual attachment. To learn more, see Office 365 now supports larger email messages.

    Note

    Particular email clients may have lower message size limits or may limit the size of an individual file attachment to a value that is less than the Exchange Online message size limit.

  • Subject length limit The maximum number of text characters allowed in the subject line of an email message.

  • File attachments limit The maximum number of file attachments allowed in an email message. Even if the total size of all the file attachments doesn't violate the message size limit, there is still a limit on how many attachments are allowed in the message. This limit is controlled by the multipart message limit.

  • File attachment size limit The maximum file size of a single attachment.

    Note

    This is the maximum file size of a single attachment. Individual client programs, including Outlook Web App, may limit the size of attachments below this maximum. Exchange ActiveSync does not implement attachment size limits on an individual attachment basis. The total size of all attachments to an Exchange ActiveSync message must be less than the message size limit.

  • Multipart message limit The maximum number of message body parts that are allowed in a MIME multipart message. This limit also controls the maximum number of file attachments that are allowed in a message.

  • Embedded message depth limit The maximum number of forwarded email messages that are allowed in an email message.

Message limits across Office 365 options

Feature
Office 365 Business Essentials
Office 365 Business Premium
Office 365 Enterprise E1
Office 365 Enterprise E3
Office 365 Enterprise E5
Office 365 Enterprise F1
Message size limit - Outlook
150 MB1, 2
150 MB1, 2
150 MB1, 2
150 MB1, 2
150 MB1, 2
150 MB1, 2
Message size limit - OWA
112 MB1, 3
112 MB1, 3
112 MB1, 3
112 MB1, 3
112 MB1, 3
112 MB1, 3
Message size limit - Outlook for Mac
150 MB1, 2
150 MB1, 2
150 MB1, 2
150 MB1, 2
150 MB1, 2
150 MB1, 2
Message size limit - migration
150 MB 4
150 MB 4
150 MB 4
150 MB 4
150 MB 4
150 MB 4
Size limit for encrypted messages (for subscribers using Office 365 Message Encryption with new capabilities)5
150 MB
150 MB
150 MB
150 MB
150 MB
150 MB
Size limit for encrypted messages (for subscribers using Office 365 Message Encryption legacy version)5
25 MB
25 MB
25 MB
25 MB
25 MB
25 MB
Subject length limit
255 characters
255 characters
255 characters
255 characters
255 characters
255 characters
File attachments limit
250 attachments
250 attachments
250 attachments
250 attachments
250 attachments
250 attachments
File attachment size limit - Outlook
150 MB
150 MB
150 MB
150 MB
150 MB
150 MB
File attachment size limit - OWA 6
35 MB
35 MB
35 MB
35 MB
35 MB
35 MB
File attachment size limit - Outlook for Mac
150 MB
150 MB
150 MB
150 MB
150 MB
150 MB
Multipart message limit
250 parts
250 parts
250 parts
250 parts
250 parts
250 parts
Embedded message depth limit
30 embedded messages
30 embedded messages
30 embedded messages
30 embedded messages
30 embedded messages
30 embedded messages

Note

1 The default maximum message size for Office 365 mailboxes is 25 MB. Office 365 Administrators can specify a custom limit between 1 MB and 150 MB. However, the size of message you can send or receive also depends on what your email client or solution supports. For more information about customizing the maximum allowed message size for your organization, see Office 365 now supports larger email messages.
2 You can send and receive up to 150 MB messages between Office 365 users (where the message never leaves the Office 365 datacenters). Messages that are routed outside of the Office 365 datacenters are subject to an additional 33% translation encoding increase, in which case the maximum message size is 112 MB.
3 OWA accounts for the possibility that your message may be subject to the 33% encoding increase and restricts the size of message you can send to 25% less than the configured setting. For example, if you customize your settings for a 100 MB maximum message size, you can send messages no larger than 75 MB.
4 The size of messages to be moved into Exchange Online are computed by Exchange Online. Versions of Exchange prior to Exchange Server 2013 may report a smaller item size. This limit applies to move based migrations using any supported Exchange Mailbox Replication Service. Other migration methods (Cutover, Staged, IMAP, PST) and other third party tools are limited by the general message size limit.
5 For information about OME with new capabilities, see Set up new Office 365 Message Encryption capabilities built on top of Azure Information Protection.
6 You cannot attach a single file that exceeds 35 MB. Additionally, you cannot attach files that collectively exceed 35MB. For example, if you attach one 34MB file, you can only attach an additional 1 MB file.

Message limits across standalone options

Feature
Exchange Server 2013
Exchange Online Plan 1
Exchange Online Plan 2
Exchange Online Kiosk
Message size limit - Outlook
10 MB4
150 MB1, 2
150 MB1, 2
150 MB2
Message size limit - OWA
10 MB4
112 MB1, 3
112 MB1, 3
150 MB1, 2
Message size limit - Outlook for Mac
10 MB4
150 MB
150 MB
Message size limit - migration
Not applicable
150 MB 5
150 MB 5
150 MB 5
Size limit for encrypted messages (for subscribers using Office 365 Message Encryption with new capabilities)6
150 MB
150 MB
150 MB
150 MB
Size limit for encrypted messages (for subscribers using Office 365 Message Encryption legacy version)6
25 MB
25 MB
25 MB
25 MB
Subject length limit
255 characters
255 characters
255 characters
255 characters
File attachments limit
1024 attachments4
250 attachments
250 attachments
250 attachments
File attachment size limit - Outlook
35 MB4
150 MB
150 MB
150 MB
File attachment size limit - OWA
35 MB4
35 MB
35 MB
35 MB
File attachment size limit - Outlook for Mac
35 MB4
150 MB
150 MB
35 MB
Multipart message limit
250 parts
250 parts
250 parts
250 parts
Embedded message depth limit
30 embedded messages
30 embedded messages
30 embedded messages
30 embedded messages

Note

1 Office 365 Administrators can specify a custom limit between 1 MB and 150 MB. However, the size of message you can send or receive also depends on what your email client or solution supports. For more information about customizing the maximum allowed message size for your organization, see Office 365 now supports larger email messages.
2 You can send and receive up to 150 MB messages between Office 365 users (where the message never leaves the Office 365 datacenters). Messages that are routed outside of the Office 365 datacenters are subject to an additional 33% translation encoding increase, in which case the maximum message size is 112 MB.
3 OWA accounts for the possibility that your message may be subject to the 33% encoding increase and restricts the size of message you can send to 25% less than the configured setting. For example, if you customize your settings for a 100 MB maximum message size, you can send messages no larger than 75 MB.
4 This is the default limit for Exchange Server 2013 organizations. Administrators can change this value for their organization.
5 The size of messages to be moved into Exchange Online are computed by Exchange Online. Versions of Exchange prior to Exchange Server 2013 may report a smaller item size.
6 For information about OME with new capabilities, see Set up new Office 365 Message Encryption capabilities built on top of Azure Information Protection.

Receiving and sending limits

Receiving and sending limits are applied to combat spam and mass-mailing worms or viruses. These limits help to protect the health of our systems and keep our users safe.

Receiving limits

Receiving limits apply to the number of messages that a user, group, or public folder can receive per hour. This applies for both messages received from the Internet and from on-premises servers. When the receiving limit has been exceeded, any emails sent to that mailbox will receive a non-delivery report stating that the mailbox has exceeded the maximum delivery threshold. After one hour, the limit will refresh and the mailbox will once again be able to receive messages.

Feature
Office 365 Business Essentials
Office 365 Business Premium Office
Office 365 Enterprise E1
Office 365 Enterprise E3
Office 365 Enterprise E5
Office 365 Enterprise F1
Messages received
3,600 messages per hour
3,600 messages per hour
3,600 messages per hour
3,600 messages per hour
3600 messages per hour
3600 messages per hour

Sending limits

Sending limits apply to the number of recipients, number of messages, and number of recipients per message that a user can send from their Exchange Online account.

Note

For distribution groups stored in an organization's address book, the group is counted as one recipient. For distribution groups stored in the Contacts folder of a mailbox, the members of the group are counted individually.

  • Recipient rate limit To discourage the delivery of unsolicited bulk messages, Exchange Online has recipient limits that prevent users and applications from sending large volumes of email. These limits are applied per-user to all outbound and internal messages.

    Note

    Exchange Online customers who need to send legitimate bulk commercial email (for example, customer newsletters) should use third-party providers that specialize in these services.

  • Recipient limit This is the maximum number of recipients allowed in the To:, Cc:, and Bcc: fields for a single email message.

    Note

    For the purposes of the recipient rate limit and the recipient limit, a distribution group that is stored in the organization's shared address book counts as one recipient. In a personal distribution list, each recipient is counted separately.

  • Message rate limit Message rate limits determine how many messages a user can send from their Exchange Online account within a specified period of time. This limit helps prevent overconsumption of system resources by a single sender. If a user submits messages at a rate that exceeds the limit via SMTP client submission, the messages will be rejected and the client will need to retry.

Sending limits across Office 365 options

Feature
Office 365 Business Essentials
Office 365 Business Premium
Office 365 Enterprise E1
Office 365 Enterprise E3
Office 365 Enterprise E5
Office 365 Enterprise F1
Recipient rate limit
10,000 recipients per day
10,000 recipients per day
10,000 recipients per day
10,000 recipients per day
10,000 recipients per day
10,000 recipients per day
Recipient limit
500 recipients
500 recipients
500 recipients
500 recipients
500 recipients
500 recipients
Recipient proxy address limit
400
400
400
400
400
400
Message rate limit (SMTP client submission only)
30 messages per minute
30 messages per minute
30 messages per minute
30 messages per minute
30 messages per minute
30 messages per minute

Sending limits across standalone options

Feature
Exchange Server 2013
Exchange Online Plan 1
Exchange Online Plan 2
Exchange Online Kiosk
Recipient rate limit
No limit1
10,000 recipients per day
10,000 recipients per day
10,000 recipients per day
Recipient limit
500 recipients1
500 recipients
500 recipients
500 recipients
Recipient proxy address limit
400
400
400
400

Note

1 This is the default limit for Exchange Server 2013 organizations. Administrators can change this value for their organization.

Reporting and message trace limits

For reporting and message trace limits, see the "Reporting and message trace data availability and latency" section in Reporting and Message Trace in Exchange Online Protection.

Retention limits

These limits control the length of time that items in specific folders in the Inbox can be accessed.

  • Deleted Items folder retention period The maximum number of days that items can remain in the Deleted Items folder before they're automatically removed.

  • Retention period for items removed from the Deleted Items folder The maximum numbers of days that items removed from the Deleted Items folder are retained before they're permanently deleted.

  • Junk Email folder retention period The maximum number of days that items can remain in the Junk Email folder before they're automatically removed.

Retention limits across Office 365 options

Feature
Office 365 Business Essentials
Office 365 Business Premium
Office 365 Enterprise E1
Office 365 Enterprise E3
Office 365 Enterprise E5
Office 365 Enterprise F1
Deleted Items folder retention period
No limit1
No limit1
No limit1
No limit1
No limit1
No limit1
Retention period for items removed from the Deleted Items folder
14 days1
14 days1
14 days1
14 days1
14 days1
14 days1
Junk Email folder retention period
30 days
30 days
30 days
30 days
30 days
30 days

Note

1 This is the default limit. Administrators can change this value for their organization.

Retention limits across standalone options

Feature
Exchange Server 2013
Exchange Online Plan 1
Exchange Online Plan 2
Exchange Online Kiosk
Deleted Items folder retention period
No limit1
No limit1
No limit1
No limit1
Retention period for items removed from the Deleted Items folder
14 days1
14 days2
14 days2
14 days2
Junk Email folder retention period
2 years1
30 days
30 days
30 days

Note

1 This is the default limit. Administrators can change this value for their organization.
2 This is the default value for Exchange Online organizations. Administrators can change this value to a maximum of 30 days for mailboxes in their organization.

Distribution group limits

These limits apply to distribution groups in your organization's shared address book.

  • Maximum number of distribution group members The total recipient count is determined after distribution group expansion.

  • Limit sending messages to large distribution groups Distribution groups that contain the number of members specified by this limit must have delivery management or message approval options configured. Delivery management specifies a list of senders who are allowed to send messages to the distribution group. Message approval specifies one or more moderators who must approve all messages sent to the distribution group.

  • Maximum message size for large distribution groups If a message is sent to 5,000 or more recipients, the message size can't exceed this limit. If the message size exceeds the limit, the message isn't delivered, and the sender receives a non-delivery report (NDR). The total recipient count is determined after distribution group expansion.

Distribution group limits across Office 365 options

Feature
Office 365 Business Essentials
Office 365 Business Premium
Office 365 Enterprise E1
Office 365 Enterprise E3
Office 365 Enterprise E5
Office 365 Enterprise F1
Maximum number of distribution group members1
100,000 members
100,000 members
100,000 members
100,000 members
100,000 members
100,000 members
Limit sending messages to large distribution group
5,000 or more members
5,000 or more members
5,000 or more members
5,000 or more members
5,000 or more members
5,000 or more members
Maximum message size for distribution groups with 5,000 to 100,000 members
25 MB
25 MB
25 MB
25 MB
25 MB
25 MB
Maximum message size for distribution groups with 100,000 or more members
5 MB
5 MB
5 MB
5 MB
5 MB
5 MB
Maximum number of distribution group owners
10
10
10
10
10
10
Maximum number of groups a user can create
300,0002
300,0002
300,0002
300,0002
300,0002
300,0002

Note

1 If you are using Azure Active Directory DirSync, the maximum number of distribution group members that you can synchronize from your on-premises Active Directory to Azure Active Directory is 15,000. If you are using Azure AD Connect, that number is 50,000.
2 This limit also applies to admins.

Distribution group limits across standalone options

Feature
Exchange Server 2013
Exchange Online Plan 1
Exchange Online Plan 2
Exchange Online Kiosk
Maximum number of distribution group members
100,000 members1
100,000 members
100,000 members
100,000 members
Limit sending messages to large distribution group
5,000 or more members1
5,000 or more members
5,000 or more members
5,000 or more members
Maximum number of distribution group owners
10
10
10
10
Maximum number of groups a user can create
2502
2502
2502
2502

Note

1 This is the default limit for Exchange Server 2013 organizations. Administrators can change this value for their organization.
2 This limit also applies to admins.

Journal, Transport, and Inbox rule limits

The following list includes limits that apply to journal rules, transport rules (also known as organization-wide rules), and limits that apply to Inbox rules. Inbox rules are set up by individual users and applied to messages sent and received by the individual user's mailbox.

  • Maximum number of journal rules The maximum number of journal rules that can exist in the organization.

  • Maximum number of transport rules The maximum number of rules that can exist in the organization.

  • Maximum size of an individual transport rule The maximum number of characters that can be used in a single transport rule. The characters are used in the conditions, exceptions, and actions.

  • Character limit for all regular expressions used in all transport rules The total number of characters used by all the regular expressions in all the transport rule conditions and exceptions in the organization. You can have a few rules that use long and complex regular expressions, or you can have many rules that use simple regular expressions.

  • Scanning limits for attachment content The transport rule conditions enable you to examine the content of message attachments, but only the first 1 MB of the text extracted from an attachment is inspected. This 1 MB limit refers to the text extracted from the attachment, not to the file size of the attachment. For example, a 2 MB file may contain less than 1 MB of text, so all of the text would be inspected

  • Maximum number of recipients added to a message by all transport rules When a message is acted on by different transport rules, only a finite number of recipients can be added to the message. After the limit is reached, any remaining recipients aren't added to the message. Also, distribution groups can't be added to a message by a transport rule.

  • Forwardee limit The maximum number of recipients that can be configured for an inbox or transport rule with a redirecting action. If a rule is configured to redirect a message to more than this number of recipients, the rule won't be applied and any message that satisfies the rule condition won't be redirected to any of the recipients listed in the rule.

  • Number of times a message is redirected The number of times a message will be redirected, forwarded, or replied to automatically based on Inbox rules. For example, User A has an Inbox rule that redirects messages to User B, based on the sender. User B has an Inbox rule that forwards messages to User C based on keywords in the subject line. If a message satisfies both of these conditions, the message is only sent to User B; it's not forwarded to User C because only one redirection is allowed. In this case, the message is dropped without sending a non-delivery report (NDR) to User B indicating that the message wasn't delivered to User C.

Journal, Transport, and Inbox rule limits across Office 365 options

Feature
Office 365 Business Essentials
Office 365 Business Premium
Office 365 Enterprise E1
Office 365 Enterprise E3
Office 365 Enterprise E5
Office 365 Enterprise F1
Maximum number of journal rules
10 rules
10 rules
10 rules
10 rules
10 rules
10 rules
Maximum number of transport rules
300 rules
300 rules
300 rules
300 rules
300 rules
300 rules
Maximum size of an individual transport rule
8 KB
8 KB
8 KB
8 KB
8 KB
8 KB
Character limit for all regular expressions used in all transport rules
20 KB
20 KB
20 KB
20 KB
20 KB
20 KB
Scanning limits for content of attachments
1 MB
1 MB
1 MB
1 MB
1 MB
1 MB
Maximum number of recipients added to a message by all transport rules
100 recipients
100 recipients
100 recipients
100 recipients
100 recipients
100 recipients
Forwardee limit
10 recipients
10 recipients
10 recipients
10 recipients
10 recipients
10 recipients
Number of times a message is redirected
1 redirection
1 redirection
1 redirection
1 redirection
1 redirection
1 redirection

Journal, Transport, and Inbox rule limits across standalone options

Feature
Exchange Server 2013
Exchange Online Plan 1
Exchange Online Plan 2
Exchange Online Kiosk
Maximum number of journal rules
No limit
10 rules
10 rules
10 rules
Maximum number of transport rules
No limit
300 rules
300 rules
300 rules
Maximum size of an individual transport rule
40 KB
8 KB
8 KB
8 KB
Character limit for all regular expressions used in all transport rules
No limit
20 KB
20 KB
20 KB
Maximum number of recipients added to a message by all transport rules
No limit
100 recipients
100 recipients
100 recipients
Forwardee limit
No limit
10 recipients
10 recipients
10 recipients
Number of times a message is redirected
3 redirections
1 redirection
1 redirection
1 redirection

Moderation limits

These limits control the moderation settings that are used for message approval applied to distribution groups and transport rules.

  • Maximum size of the arbitration mailbox If the arbitration mailbox exceeds this limit, messages that require moderation are returned to the sender in a non-delivery report (NDR).

  • Maximum number of moderators The maximum number of moderators that you can assign to a single moderated distribution group or that can be added to a message using a single transport rule. Note that you can't specify a distribution group as a moderator.

  • Expiration for messages waiting for moderation By default, a message waiting for moderation expires after two days. However, the processing of expired moderated messages runs every seven days. This means that a moderated message can expire at any time between two and nine days.

  • Maximum rate for expired moderation notification messages This limit sets the maximum number of notification messages for expired moderated messages in a one-hour period. This limit is placed on each mailbox database in the datacenter.

    During periods of heavy usage, some senders may not receive notification messages for moderated messages that have expired. However, these notifications are still discoverable using delivery reports.

Moderation limits across Office 365 options

Feature
Office 365 Business Essentials
Office 365 Business Premium
Office 365 Enterprise E1
Office 365 Enterprise E3
Office 365 Enterprise E5
Office 365 Enterprise F1
Maximum size of the arbitration mailbox
10 GB
10 GB
10 GB
10 GB
10 GB
10 GB
Maximum number of moderators
10 moderators
10 moderators
10 moderators
10 moderators
10 moderators
10 moderators
Expiration for messages waiting for moderation
2 days
2 days
2 days
2 days
2 days
2 days
Maximum rate for expired moderation notification messages
300 expiration notifications per hour
300 expiration notifications per hour
300 expiration notifications per hour
300 expiration notifications per hour
300 expiration notifications per hour
300 expiration notifications per hour

Moderation limits across standalone options

Feature
Exchange Server 2013
Exchange Online Plan 1
Exchange Online Plan 2
Exchange Online Kiosk
Maximum size of the arbitration mailbox
No limit1
10 GB
10 GB
10 GB
Maximum number of moderators
No limit
10 moderators
10 moderators
10 moderators
Expiration for messages waiting for moderation
5 days1
2 days
2 days
2 days
Maximum rate for expired moderation notification messages
300 expiration notifications per hour
300 expiration notifications per hour
300 expiration notifications per hour
300 expiration notifications per hour

Note

1 This is the default limit for Exchange Server 2013 organizations. Administrators can change this value for their organization.

Exchange ActiveSync limits

The following limits apply to Microsoft Exchange ActiveSync, a client protocol that synchronizes mailbox data between mobile devices and Exchange.

  • Exchange ActiveSync device limit The maximum number of Exchange ActiveSync devices per mailbox.

  • Exchange ActiveSync device deletion limit The maximum number of Exchange ActiveSync devices that an Exchange administrator can delete in a single month.

  • Exchange ActiveSync file attachment limit The maximum size of a message file attachment that can be sent or received by an Exchange ActiveSync device.

Exchange ActiveSync limits across Office 365 options

Feature
Office 365 Business Essentials
Office 365 Business Premium
Office 365 Enterprise E1
Office 365 Enterprise E3
Office 365 Enterprise E5
Office 365 Enterprise F1
Exchange ActiveSync device limit
100
100
100
100
100
100
Exchange ActiveSync device deletion limit
20
20
20
20
20
20
Exchange ActiveSync file attachment limit
25 MB
25 MB
25 MB
25 MB
25 MB
25 MB

Exchange ActiveSync limits across standalone options

Feature
Exchange Server 2013
Exchange Online Plan 1
Exchange Online Plan 2
Exchange Online Kiosk
Exchange ActiveSync device limit
100
100
100
100
Exchange ActiveSync device deletion limit
20
20
20
20
Exchange ActiveSync file attachment limit
25 MB
25 MB
25 MB
25 MB