Using Microsoft Office365 SMTP Server to Send Emails Error: 554 error: 554 5.2.0 STOREDRV.Submission.Exception:SendAsDeniedException.MapiExceptionSendAsDenied; Failed to process message due to a permanent exception with message Cannot submit message.Issue When using a Microsoft Office365 SMTP server to send emails from the instance different email addresses are set in the "From" field. One or some of the settings for "From" work fine and the email is sent without issue, but other settings fail putting the email into a send-failed state. This is the error seen in the email record: 554 error: 554 5.2.0 STOREDRV.Submission.Exception:SendAsDeniedException.MapiExceptionSendAsDenied; Failed to process message due to a permanent exception with message Cannot submit message.ReleaseApplies to any release.CauseThe Microsoft Office365 SMTP server is rejecting the set "From" address.ResolutionThis issue needs to be addressed by Mircosoft. The customer should contact Microsoft Support, showing them the error and asking how the email server can be configured to accept multiple "From" addresses.