We run DNN Platform Version 09.02.01 in a Microsoft Azure App Service. We also run Microsoft Office 365. Our DNN Platform SMTP Server Settings are configured to route emails through Office 365 Exchange Online.
Recently, we became aware that emails sent through our DNN Site were not getting routed to our internal support teams. When we investigated the issue and ran Test SMTP Settings under Server Settings, the system reported the following error:
There is a problem with the configuration of your SMTP Server. Mail was not sent. Transaction failed. The server response was: 5.2.0 STOREDRV.Submission.Exception:SendAsDeniedException.MapiExceptionSendAsDenied; Failed to process message due to a permanent exception with the message Cannot submit message.
This error came as a surprise to us, as the system worked previously without issue. Below are the SMTP Server configuration settings for our DNN Site. Please note the SMTP Username and SMTP Password are tied to a fully licensed user account in Office 365.
SMTP Server and port: smtp.office365.com:587
Connection Limit: 2
Max Idle Time: 100,000
SMTP Username: email@example.com
SMTP Password: userpassword
SMTP Enable SSL: On
We would welcome any thoughts, advice, or input on this matter. Many thanks in advance for the collaborative support.