Should I retry a 571 5.7.1 error?

No. 571 is a permanent failure, so the message will never be delivered no matter how many times you try. Remove the address — repeated sends to permanent failures are one of the main signals mailbox providers use to throttle a sender.

How do I fix SMTP 571 5.7.1?

Check your SPF, DKIM and DMARC first — authentication failure against a strict recipient is the most common cause you can actually fix.

Permanent failure — do not retry

SMTP 571 5.7.1

delivery not authorized, message refused

SMTP 571 5.7.1 is a policy refusal: the receiving server will not accept your message and will not retry. It usually means an organisational rule blocked the sender — a domain-level block, a geographic restriction, or a rule against unsolicited external mail.

How it appears

571 5.7.1 Message refused by policy

571 5.7.1 Delivery not authorized, message refused

571 5.7.1 Sender domain is blocked at this organization

What causes it

The recipient organisation blocks your sending domain or IP explicitly.
A rule refuses external mail to that address entirely, common on internal-only aliases.
Your message failed the recipient's authentication requirements.
The recipient gateway blocks by region or by sender category.

How to fix it

In order — try the first one first.

Check your SPF, DKIM and DMARC first — authentication failure against a strict recipient is the most common cause you can actually fix.
Read the text after the code. Organisations refusing mail on policy grounds usually say so, and some name a contact for allowlisting.
If one organisation blocks you wholesale, no amount of retrying or list cleaning changes it. Suppress that domain and reach them another way.
A sudden 571 across many domains points at a blocklist listing rather than individual policies.

Common questions

What does SMTP 571 5.7.1 mean?: SMTP 571 5.7.1 is a policy refusal: the receiving server will not accept your message and will not retry. It usually means an organisational rule blocked the sender — a domain-level block, a geographic restriction, or a rule against unsolicited external mail.
Should I retry a 571 5.7.1 error?: No. 571 is a permanent failure, so the message will never be delivered no matter how many times you try. Remove the address — repeated sends to permanent failures are one of the main signals mailbox providers use to throttle a sender.
How do I fix SMTP 571 5.7.1?: Check your SPF, DKIM and DMARC first — authentication failure against a strict recipient is the most common cause you can actually fix.

Last reviewed 2026-09-11