Enhanced SMTP status code · RFC 3463 · IANA
5.0.350 Generic error, x-dg-ref header is too long , or Requested action not taken: policy violation detected (AS345)
A generic error from the recipient's organisation; the text after the code gives the reason (for example an x-dg-ref header too long in Rich Text mail, or nested attachments).
- Class: Permanent failure
Class 5: a permanent failure. Resending the same message will not help: something about the message, the sender or the destination must change (RFC 3463 §3.1).
- Subject: X.0 · No specific subject
No additional subject information is available.
How 5.0.350 appears at providers
The exact text from the provider's documentation, as you see it in the bounce, and what it means.
Microsoft 365 / Exchange Online
-
5.0.350
Generic error, x-dg-ref header is too long , or Requested action not taken: policy violation detected (AS345)
A generic error from the recipient's organisation; the text after the code gives the reason (for example an x-dg-ref header too long in Rich Text mail, or nested attachments).
Have the whole error message?
Sources: RFC 5321 · RFC 3463 · RFC 3464 · IANA · Gmail · Microsoft 365 · read on 26 September 2026