554 5.2.252 / 550 5.7.60: Send As permission denied

Microsoft 365SMTP

The error usually looks like this:

554 5.2.0 STOREDRV.Submission.Exception:SendAsDeniedException.MapiExceptionSendAsDenied; Failed to process message due to a permanent exception with message Cannot submit message.

What it means

You signed in as one user but tried to send from a different address, and that user does not have permission to send as it.

Common causes

  • The From address in your app is different to the account you sign in with.
  • The account has not been given Send As permission for the shared mailbox, group or alias.

How to fix it

  1. Change the From address to match the signed-in account.
  2. Or ask an administrator to grant Send As permission (Exchange admin center → Recipients → Mailboxes → Delegation).

See also our guide: Account delegation.

Tools to help diagnose it

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