A user does not appear in the All Eligible Users list within the Dynamics 365 App for Outlook area

When viewing the Dynamics 365 App for Outlook section within Settings, a user does not appear in the All Eligible Users list.

Cause 1: The user does not have a security role assigned that includes the Use Dynamics 365 App for Outlook privilege

NOTE: Dynamics 365 App for Outlook is supported for User mailboxes. Queue mailboxes are not supported.

Cause 2: The user is not configured to use Server-Side Synchronization for Incoming Emails.

Resolution 1: Verify the user has at least one Dynamics 365 security role assigned which includes the Use Dynamics 365 App for Outlook privilege.

NOTE: The Use Dynamics 365 App for Outlook privilege is located on the Business Management tab of a security role within the Privacy Related Privileges section. 

For information about how to assign a security role, see Assign a security role to a user. For information about creating or modifying a security role, see Create or edit a security role to manage access.

Resolution 2: Verify the user's mailbox record in Dynamics 365 is configured to use Server-Side Synchronization for Incoming Email and the mailbox is Tested and Enabled successfully.

1. Access Dynamics 365 as a user with the System Administrator role.
2. Navigate to Settings and then click Email Configuration. 
3. Click Mailboxes and then change the view to Active Mailboxes. 
4. Locate and open the mailbox record for the user.
5. Verify the Incoming Email option is set to Server-Side Synchronization or Email Router.
6. If the Incoming Email Status does not already show as Success, click Test & Enable Mailbox and make sure to select the checkbox that appears in the dialog. 
7. If the mailbox tests do not succeed, review the messages in the Alerts section. If an alert includes a Learn More link, click this link for additional details.