550 5.7.1: refused on policy grounds
By Jose Pollman · Published
Hard bounceYour sending reputation
The error
550 5.7.1 Delivery not authorized, message refused
550 5.7.1 Unable to relay
550 5.7.1 Message rejected due to the sender's DMARC policyWhat it means
The receiver refused to deliver the message for policy reasons. 5.7.1 is the most overloaded code in email — it covers authentication failures, relaying denials, blocklists, content rules and DMARC rejections.
The receiver is refusing your mail because of how your sending IP or domain behaves, not because of this particular message.
Why it happens
Because it is so overloaded, the numeric code on its own tells you almost nothing. The accompanying text is what identifies the cause, which is exactly why provider-specific matching matters more here than anywhere else.
How to fix it
- Read the full text of the bounce — it names the cause where the code does not.
- If it mentions authentication, SPF, DKIM or DMARC, start with your authentication records.
- If it mentions relaying, your server is trying to send through a system that will not relay for it.
- If it names a blocklist, check whether your sending IP is listed and request delisting.
Related guides
- 554: the transaction failed — A catch-all permanent failure, most often used for content and reputation rejections. The text carries the reason.
- Gmail 550 5.7.25: the sending IP has no PTR record — Gmail blocked the message because the IP it arrived from has no reverse DNS record, or the record it has does not resolve back to that same IP.
- Microsoft 5.7.606: banned sending IP — Microsoft has blocklisted the IP you are sending from. The codes 5.7.606 through 5.7.649 all mean the same thing; the varying number identifies which internal list caught it.