The email message "Your mailbox is now connected to Dynamics 365" cannot be sent because the mailbox [Mailbox Name] is deactivated or disabled for outgoing email

This article provides a solution to an error that occurs after you select the Test & Enable Mailbox button in Microsoft Dynamics 365.

Applies to:   Microsoft Dynamics 365
Original KB number:   4481318

Symptoms

After you select the Test & Enable Mailbox button in Dynamics 365, the tests fail and the following alert is logged:

"The email message "Your mailbox is now connected to Dynamics 365" cannot be sent because the mailbox [Mailbox Name] is deactivated or disabled for outgoing email.
Email Server Error Code: MailboxDisabled"

Cause

This error occurs if the mailbox is deactivated and the status is now Inactive.

A mailbox could have been deactivated by someone selecting the Deactivate button. If it's a user mailbox, the mailbox could have been deactivated automatically if the regarding user was deactivated. For example: If you remove a user's Dynamics 365 license, the user will be deactivated and also their mailbox record.

Resolution

1. Select the Activate button on the mailbox record and verify the status shown in the footer of the page shows as Active.
2. Select the Test & Enable Mailbox button.
3. If the tests don't succeed, review the alerts that appear.

Important

If the mailbox had been deactivated because the associated user was disabled, you should also make sure the user is enabled with a valid Dynamics 365 license and security role.