554 5.7.1 error: message refused on policy
554 5.7.1 is a permanent policy refusal: the transaction failed and the sender wasn't authorized. The reason is in the text after the code.
What 554 5.7.1 means
554 Transaction failed; 5.7.1 Delivery not authorized, message refused554 is the generic "transaction failed" reply (RFC 5321); 5.7.1 says delivery wasn't authorized (RFC 3463). Neither Google nor Microsoft lists it in their tables; servers that use it put the reason in free text.
List problem or sender problem?
Depends on the text. It's a generic policy refusal. The free text after the code decides whether it's your reputation, your content or a policy on their side. It's a permanent failure: the server won't accept this message if you send it again unchanged.
How to fix 554 5.7.1
- Read the text after the code: it decides whether it's your reputation, your content or a policy on their side.
- Handle it like the matching 550 5.7.1 case.
- Don't resend the same message unchanged: it's permanent.
In SendingOS, 554 5.7.1 shows on the conversation with its reason and code, so a problem on their side never gets mistaken for one on yours.
Not sure whether a spike in bounces is the list or the domain? Read High email bounce rate? Burned domain or bad list.