What 550 5.7.1 means
The message Gmail attaches to this code is “The user or domain that you are sending to (or from) has a policy that prohibits the email that you sent.”, as written on its reference page. The first digit says how final it is: a 5xx reply is permanent for that message, so the sending server gives up and returns a bounce. The enhanced status 5.7.1 says what class of problem it is: recipient policy. The recipient's organization or mailbox has a rule that refuses the message. Nothing on the sender's side changes it.
Why it happens
The receiving organization has a rule that refuses this message: a block on the sender, a rule against mail from outside the tenant, an attachment or link type it does not accept, or a mailbox configured to take mail from known contacts only. The rule belongs to the recipient, so there is nothing on the sending side to repair.
What to do first: Recipient-side policy (Workspace admin rule, group setting). Not a reputation problem.
Why warming does not fix this
Warming builds sender reputation. 550 5.7.1 in this form is a recipient policy problem, and no amount of engagement history changes it. Fix the cause and the bounce stops; warming is for what comes after, when the mail is accepted and the question becomes which folder it lands in. See how warming works for that part.
How to fix it, in order
- Nothing to fix on your side; the recipient's organization refused the message by rule
- Remove the address from sequences and, where it matters, ask the recipient for an alternative
Related codes
- 550 5.7.1 (Gmail): IP not authorized to send directly
- 550 5.7.1 (Gmail): very low sending domain reputation
- 550 5.7.1 (Microsoft): unable to relay
- 550 5.7.1 (Microsoft): delivery not authorized
- 550 5.7.1 (Gmail): likely unsolicited email
More on Gmail
- Google Workspace emails going to spam: the Postmaster-led diagnosis, dashboard by dashboard
- Gmail and Yahoo bulk sender requirements: the rules behind Google's authentication and spam-rate rejections
- Google Postmaster Tools domain reputation: what the reputation tiers and the spam rate mean
Questions about 550 5.7.1
What does 550 5.7.1 mean?
Gmail returns 550 5.7.1 with the message "The user or domain that you are sending to (or from) has a policy that prohibits the email that you sent.": policy prohibits the email. The recipient's organization or mailbox has a rule that refuses the message. Nothing on the sender's side changes it.
Is 550 5.7.1 a hard bounce or a soft bounce?
A hard bounce for that message: the 550 reply is permanent, and the message is not retried. Whether the address should be removed depends on the cause: here the fix is on the sending side, not the list.
How do I fix 550 5.7.1?
Recipient-side policy (Workspace admin rule, group setting). Not a reputation problem. Gmail's own reference for the code is linked on this page.
Does email warmup fix 550 5.7.1?
No. 550 5.7.1 in this form is a recipient policy problem, and warming builds reputation, which is not what is failing here. Fix the cause and the bounce stops.