Clients and mobile devices
Microsoft Outlook is an email program that includes support for calendar, contacts, tasks, and the following key features:
MAPI over HTTP - Messaging Application Program Interface (MAPI) over HTTP allows Outlook users to connect to Exchange Online mailboxes over the internet from outside their organization's firewall. MAPI over HTTP, the long term replacement for Outlook Anywhere. This connectivity method offers improved connection resiliency, more secure sign-in, extensibility, as well as enhancements for IT and support. To learn more, see RPC over HTTP reaches end of support in Office 365 and MAPI over HTTP.
Autodiscover - The Autodiscover service feature automatically configures Outlook to work with Exchange Online. Outlook users can receive their required profile settings directly from Exchange Online the first time they sign in with their email address and password. These settings automatically update the Outlook client with the information necessary to create and maintain the user's profile. An SSL certificate is required to use the Autodiscover service. This SSL certificate is limited to a single primary SSL domain.
Cached Exchange Mode - The Cached Exchange Mode feature allows Outlook users to access local copies of their Exchange Online mailboxes when they are not connected to the internet. Cached Exchange Mode retains a client-side copy of users' Exchange mailboxes in Outlook and automatically synchronizes this copy with the email server. We recommend using Outlook in Cached Exchange Mode because it provides offline access and helps to provide a responsive user experience even when network conditions between the client and the server are not ideal.
By default, Outlook access is enabled for all users. Administrators can disable access for specific users or groups through Windows PowerShell. We recommend using the latest version of Outlook—with the latest service pack installed—to access Exchange Online.
For information about which Outlook clients are supported by Exchange 2016 and Exchange Online, see System Requirements for Office.
Microsoft 365 is designed to work with the latest browsers and versions of Office. If you use older browsers and versions of Office that aren't in mainstream support:
- Microsoft won't deliberately prevent you from connecting to the service, but the quality of your experience may diminish over time.
- Microsoft won't provide software updates to resolve non-security related problems.
Outlook is not provided as part of the Exchange Online subscription price. Microsoft 365 Apps for enterprise (which includes Microsoft Outlook) is included in some plans and can be purchased as a separate subscription. You will see the following limitations if you use POP to connect to an Exchange Online email account:
- No calendar information
- No free/busy information
- No Global Address List
- No push email
- When connecting through POP, all messages will be downloaded to the client and there will be no synchronization between multiple computers or devices (such as between a laptop and a phone).
Outlook on the web
Outlook on the web is a web-based version of the Outlook email program that is used with Exchange Online. It lets users access their email, calendar, and contacts through a web browser from wherever they connect to the internet. For information about supported browsers, see Supported browsers for Outlook on the web for business.
Outlook on the web comes in two client versions, both of which can be used with Exchange Online:
Outlook on the web - The standard version of Outlook on the web provides Exchange Online users with a messaging experience most similar to that of Outlook users. It supports most newer web browsers and is optimized for use on tablets and smartphones as well as desktops and laptops. Users can read and send messages, organize contacts, and schedule appointments and meetings. The default activity-based time-out is set at six hours, but it can be configured by an administrator in Windows PowerShell from 5 minutes to 8 hours. This time-out depends on user interactions within the web app, such as selecting a button or selecting a message. There is also a separate security-driven time-out, which is not configurable and will occur regardless of user activity. If a user is logged in for 8 hours, OWA will automatically log the user out and ask for re-authentication.
The light version of Outlook on the web - The light version of Outlook on the web provides Exchange Online users access to the mailbox using almost any web browser. Users can read and send messages, organize contacts, and schedule appointments and meetings. The default activity-based time-out is set at six hours, but it can be configured by an administrator in Windows PowerShell from 5 minutes to 8 hours. This time-out depends on user interactions within the web app, such as selecting a button or selecting a message. There is also a separate security-driven time-out, which is not configurable and will occur regardless of user activity. If a user is logged in for 8 hours, the light version of OWA will automatically log the user out and ask for re-authentication.
Outlook on the web also is available in mobile versions. For more information, see this page.
Outlook for Mac
Exchange Online supports Microsoft Outlook for Mac, which provides email, calendar, an address book, a task list, and a note list.
Outlook for iOS, Android, and Windows Phone
Exchange Online works with Outlook apps available for iOS, Android, and Windows Phone. On any of these devices, use the app store to find the Outlook app. Here's a breakdown by mobile OS.
|Outlook mobile app availability
Get Outlook for Android
Get Outlook for iOS
|Built-in email apps compatible with Exchange Online
||Gmail app/Samsung Email app
||iOS Mail app
||Outlook Mail, calendar, contacts
||Android mobile setup
||iPhone or iPad setup
||Windows Phone setup
There are also options for using Exchange Online with devices, including Blackberry.
Outlook gives users the fast, intuitive email and calendar experience that they expect from a modern mobile app, while being the only app to provide support for the best features. It is the only email app specifically designed to support the full Microsoft experience, giving users a coherent experience from desktop to mobile. Outlook is integrated with Intune, enterprise mobility and security, and Exchange controls to keep data and users safe.
With Outlook, users can:
Manage their entire day from a mobile device.
Connect to the apps and services they need to be productive, while keeping their work and personal information separate and secure.
With Outlook for iOS, Outlook for Android, or Outlook for Windows Phone, users can:
Benefit from a focused inbox that priorities important email
Customize swipe gestures to match their unique email habits
Create travel itineraries that can be added directly to the calendar, with key information available at a glance
RSVP to meetings from the inbox.
Use intuitive icons in email and calendar appointments that help them process information quickly
Use a consistent and familiar Outlook experience across all devices
Easily launch and join Skype meetings from the calendar
Read and respond to IRM encrypted and protected emails
Share files stored in OneDrive for Business
Set Automatic Replies with a tap
View and manage shared and delegated calendars
Search their company's global address list with a few taps
View coworker's availability and schedule a meeting time that works for everyone
See invitees accept, tentative, and decline status
Share calendars right from their phones
Start and join Skype meetings right from a calendar
Access work and personal calendars in one place, without switching apps
Exchange Online supports the Microsoft Exchange ActiveSync protocol, which synchronizes mailbox data between mobile devices and Exchange Online, so users can access their email, calendar, contacts, and tasks on the go.
A wide range of mobile devices work with Exchange ActiveSync, including Microsoft Windows Phone, Apple iPhone and iPad, and Android phones and tablets. In addition to mobile phones and devices, the Mail application in Windows Phone uses Exchange ActiveSync to connect to Exchange Online. A complete list of current Exchange ActiveSync licensees is available at the Exchange ActiveSync Licensing site.
For more information about Exchange ActiveSync, see Exchange ActiveSync.
The maximum number of Exchange ActiveSync devices per mailbox is 100.
Applications developed with Exchange Web Services (EWS)
Applications developed using Exchange Web Services (EWS) or the EWS Managed API let administrators access data stored with Exchange Online from applications that are running on-premises, in Azure, or in other hosted services.
For more information on applications developed with Exchange Web Services, see Web Services in Exchange.
POP and IMAP
Exchange Online supports mailbox access through both POP3 and IMAP4 protocols. POP and IMAP access requires encryption using SSL. POP is enabled by default for all users. Users can view their POP and IMAP connection settings in Outlook on the web. Administrators can disable POP and IMAP access on a per-user basis.
For more information about POP3 and IMAP4 connectivity, see POP3 and IMAP4.
Simple Mail Transfer Protocol (SMTP) is used to send outbound mail for clients that connect to Exchange Online through IMAP or POP. It is the primary protocol for routing and delivery through Exchange Server. Exchange Online supports two types of SMTP relay services for authorized internal customer applications that require SMTP mail submission:
SMTP message submission to users inside the managed environment.
Authenticated SMTP message relay to addresses outside the managed environment.
IP addresses for authorized source servers are required to allow SMTP relay. Transport Layer Security (TLS) encryption and authentication is required when using SMTP to send email.
Email is available on BlackBerry® devices via Exchange ActiveSync. To find out what your options are, see these topics:
For more information, see BlackBerry.
If you are using Office 365 operated by 21Vianet in China, BlackBerry Business Cloud Services is not available. However, you can use Exchange ActiveSync devices or an offering from Research in Motion (RIM, the BlackBerry wireless email solution) to run Blackberry Enterprise Server (BES).
To view feature availability across plans, standalone options, and on-premises solutions, see Exchange Online service description.