An error occurred in sending email for mailbox error appears when testing and enabling a mailbox in Microsoft Dynamics 365
This article provides a solution to an error that occurs when you try to test and enable a mailbox in Microsoft Dynamics 365.
Applies to: Microsoft Dynamics 365
Original KB number: 4092737
When you attempt to test and enable a mailbox in Microsoft Dynamics 365, you receive following error:
"An error occurred in sending email for mailbox "Your mailbox is now connected to Dynamics 365" while connecting to the email server. The owner of the associated email server profile <Mailbox Name> has been notified. The system will try to send email again later.
Email Server Error Code: Web server returned ConnectFailure exception."
This error can occur if Dynamics 365 is unable to connect to your email server.
If you're using Dynamics 365 Online with Exchange on-premises, it can occur if your firewall doesn't allow communication from Dynamics 365 online.
If you're using an SMTP/POP3 provider such as Gmail, it can occur if the port values within the Advanced section of the email server profile aren't correct.
Dynamics 365 Online with Exchange on-premises
Verify your firewall allows communication from Dynamics 365 online. For a list of the IP address ranges that may be used by Dynamics 365, see Microsoft Dynamics CRM Online IP Address Ranges.
POP3/SMTP Providers such as Gmail
Verify the correct ports are specified:
Navigate to Settings, Email Configuration, and then select Email Server Profiles.
Open the Email Server Profile that is used by the mailbox meeting this error.
You can also select the name of the Email Server Profile within the error message. It appears as a hyperlink which will open the correct Email Server Profile record.
Verify the Incoming Port and Outgoing Port values, and then select Save.
Refer to the documentation from your email provider for the correct ports to use when connecting to the SMTP service. For Gmail, the incoming POP3 port is 995 and outgoing SMTP port is 587.
Select Mailboxes and then select the mailbox that received the error.
Select the Test & Enable Mailboxes button.
After the tests complete, open the mailbox record and view the Alerts section if the results don't appear as Success.