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Email error 550 5.7.1: Message rejected by policy (blocked)

The receiving server refused the message because of a policy decision, not because the mailbox is missing. The sender, the sending IP or the content was judged unwanted.

Sender or policy problem

What it means

The receiving server refused the message because of a policy decision, not because the mailbox is missing. The sender, the sending IP or the content was judged unwanted.

Common causes

  • The sending IP or domain is on a blocklist.
  • SPF, DKIM or DMARC is missing or failing.
  • The message looks like spam to the filter.
  • The recipient network only accepts mail from approved senders.

How to fix it

  1. Read the text after the code: many providers name the reason or a help link.
  2. Check SPF, DKIM and DMARC for your sending domain.
  3. Check your sending IP and domain against public blocklists and request removal if listed.
  4. Reduce volume, clean the list and send only wanted content, then try again later.

How to prevent it

Most bounces come from addresses that were never checked. Verify each address before you send: syntax, domain, mailbox and risk are checked without sending a message. Test a single address with the free email checker or upload a whole list for bulk verification.

Verify an email address free · Clean a whole list · MX lookup · SPF, DKIM and DMARC checker

Frequently asked questions

Does 5.7.1 mean the address is invalid?

No. The mailbox may be fine. The rejection is about the sender or the message.

Should I remove the address?

Not automatically. Fix the sending problem first and test with a small batch.

Other error codes

550 5.1.1User unknown (mailbox does not exist) 550 5.7.26Sender not authenticated (SPF/DKIM/DMARC) 550 5.4.1Recipient address rejected: access denied 552 5.2.2Mailbox full (over quota) 553 5.1.3Invalid address syntax 554 5.7.1Transaction failed: service unavailable or blocked

All email error codes