Email fails to be sent or received when Server-Side Synchronization is configured with Gmail

Applies to: Dynamics CRM 2013Dynamics CRM 2015Dynamics CRM 2016 More


If Microsoft Dynamics CRM is configured to use Server-Side Synchronization with Gmail, you may encounter one of the following errors:
  • Email cannot be received for the mailbox <Mailbox Name>. Make sure that the credentials specified in the mailbox are correct and have sufficient permissions for receiving email. Then, enable the mailbox for email processing.
  • An unknown error occurred while sending the email message "Test Message". Mailbox <Mailbox Name> didn't synchronize. The owner of the associated email server profile <Email Server Profile Name> has been notified.


This can occur for one of the following reasons:

Cause 1: The email address, username, or password in the mailbox record in Microsoft Dynamics CRM are not correct.

Cause 2: The correct port is not configured within the Email Server Profile record in Microsoft Dynamics CRM.

Cause 3: POP is not enabled on your Gmail mailbox.

Cause 4: A setting in Gmail is preventing Server-Side Sync from authenticating to the Gmail mailbox.


Resolution 1: Verify the values of the Email Address, Username, and Password fields in the mailbox record in Microsoft Dynamics CRM.

Resolution 2: Open the Email Server Profile and then click Advanced. Set the Incoming Port to 995 and the Outgoing Port to 587.

Resolution 3: Follow the Gmail instructions for enabling POP:

Enable POP in Gmail

Resolution 4: Check your Gmail mailbox for an email regarding a blocked sign-in attempt. The message will include steps for how to unblock access. After following the steps, try testing and enabling the mailbox in CRM again. 

If the issue still occurs, refer to the following Gmail article which includes additional steps that may be necessary to enable email access from an app:

Troubleshoot sign-in problems

More Information

The details section of the Alert may include the following text:

"Error : System.Net.Mail.SmtpException: Syntax error, command unrecognized. The server response was: 
   at System.Net.Mail.SmtpConnection.ConnectAndHandshakeAsyncResult.End(IAsyncResult result)
   at System.Net.Mail.SmtpClient.ConnectCallback(IAsyncResult result)"