Email message filtering and correlation


Applies To: Dynamics 365 (online), Dynamics 365 (on-premises), Dynamics CRM 2016, Dynamics CRM Online


The information provided here is for versions of Dynamics 365 prior to Dynamics 365 (online), version 9.0. For the latest documentation, see Use Email message filtering and correlation to specify which emails are tracked.

Server-side synchronization, Microsoft Dynamics 365 for Outlook, or the Email Router can automatically create email activities in Microsoft Dynamics 365, which are based on received email messages. This type of automation is known as email message tracking. Users can select a filtering option that determines what email messages will be tracked in Microsoft Dynamics 365. Filtering is set on the Email tab of the Set Personal Options dialog box in the Microsoft Dynamics 365 client applications. Users can set the following options:

  • All email messages. All email messages received by the user are tracked (will have activities created).

  • Email messages in response to Dynamics 365 email. Only replies to email messages that have already been tracked will be saved as email activities. This option uses What is smart matching?, a correlation method that uses the existing properties contained in the email to relate email messages to activities.

  • Email messages from Dynamics 365 Leads, Contacts, and Accounts. Only email messages sent from leads, contacts, and accounts in the Microsoft Dynamics 365 database are saved as activities.

  • Email messages from Microsoft Dynamics 365 records that are email enabled. Email messages are tracked from any record type that contains an email address, including customized record types (entities).

By default, the Email messages in response to Dynamics 365 email option is enabled. Correlation occurs after an email message is filtered. System administrators can turn off all message tracking for a particular user by setting the Email Access Type - Incoming value to None on the General tab on the User form.

Email correlation is set on the Email tab of the System Settings page and can be enabled or disabled for the entire Microsoft Dynamics 365 organization. Microsoft Dynamics 365 uses two kinds of correlation, tracking tokens and smart matching. By default, both correlation types are enabled.


Tracking tokens are the only supported correlation method that can be used when you use Dynamics 365 for Outlook connected to an SMTP server and send email to a non-Exchange recipient. In this situation, if tracking tokens are not enabled, then correlation events, such as the automatically creating records based on the regarding object, may not work.

How Microsoft Dynamics 365 uses conversations to track emails

Use Exchange conversations to increase the probability for email identification and matching. Exchange groups together related email and assigns them an id (conversation id), to identify emails that are part of one conversation.

  1. Go to Settings > Administration > System Settings.

  2. Click the Email tab.

  3. In the Configure folder-level tracking and email correlation area, click Use correlation to track email conversations.

Configure folder-level tracking


If checked, this option uses the conversation id to identify all the emails that replied to a tracked email.

How Microsoft Dynamics 365 uses tracking tokens

Tracking tokens increase the probability for email identification and matching. You can use the tracking token feature to improve email message tracking. A tracking token is an alphanumeric string generated by Microsoft Dynamics 365 and appended to the end of an email subject line. It matches email activities with email messages.

Tracking tokens add an additional correlation component to smart matching. When Microsoft Dynamics 365 generates an outgoing email activity, a resulting email response arriving in the Microsoft Dynamics 365 system is then correlated to the originating activity.

By default, the tracking token feature is turned on.

Tracking token structure

By default, Microsoft Dynamics 365 uses the following token structure, that consists of a 4 character prefix and a 7 digit identifier.

Tracking token structure in Dynamics 365

The following table lists tracking token parts and descriptions.




Configurable from 1-20 characters. The default value is Dynamics 365:. The prefix can be unique for each organization or Microsoft Dynamics 365 (online) instance. For example, in a multi-tenant deployment of Microsoft Dynamics 365, we recommend that each organization configure and use a unique prefix.

Deployment base tracking number

Configurable from 0-2,147,483,647. Default value is 0. Can be used as an identifier for a specific instance, organization, or deployment of Microsoft Dynamics 365.

User number digit range

Configurable from 1-9. The default range is three (3) digits. This value determines how many digits to use when Microsoft Dynamics 365 generates the numeric identifier for the Microsoft Dynamics 365 user who generated the email activity.

Incremental message counter digit range

Configurable from 1-9. Default range is three (3) digits. This value determines how many digits to use when Microsoft Dynamics 365 generates the numeric identifier for the email activity (not the individual messages that the activity contains). If you use the default value to generate a token with a three-digit number, it will increment the number through 999, and then restart the number at 000. You can use a larger order of digits to reduce the possibility of assigning duplicate tokens to active email threads.

Although we don’t recommend it because it can significantly reduce the probability for accurate email activity to email message correlation, you can turn tacking tokens off. To enable, disable, or configure tracking tokens, do the following:

  1. Go to Settings > Administration > System Settings.

  2. Click the Email tab.

  3. In the Configure email correlation area you can disable, enable, or change the default tracking token structure.

What is smart matching?

When an incoming email message is processed by the Email Router, the system extracts information associated with the email message subject, sender address, and recipients’ addresses that link the email activity to other Microsoft Dynamics 365 records. This correlation process, also known as smart matching, uses the following criteria to match received email message information to email activities:

  • Subject matching. Prefixes, such as RE: or Re:, and letter case are ignored. For example, email message subjects with Re: hello and Hello would be considered a match.

  • Sender and recipient matching. The system calculates the number of exact sender and recipient email addresses in common.

When the matching process is complete, the system selects the owner and the object of the incoming email message.

By default, smart matching is turned on.


You can disable, enable, and tune smart-matching settings in the Help & Training: System Settings dialog box – Email tab.

See Also

Integrate (synchronize) your email system with Microsoft Dynamics 365
Forward mailbox vs. individual mailboxes

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