Sender or policy problem
Email error 554 5.7.1: Transaction failed: service unavailable or blocked
A general refusal. The server stopped the delivery for a reason that usually appears in the text after the code, such as a blocked sender, a listed IP or a content rule.
Common causes
- The sending IP is on a blocklist the recipient uses.
- The message was flagged as spam or contains a blocked link.
- The recipient server does not accept mail from your region or network.
- Too many messages were sent in a short time.
How to fix it
- Read the full bounce text and follow any link it gives.
- Check blocklists for your sending IP and domain.
- Remove suspicious links and shorten the message, then test again.
- Slow down and send fewer messages at a time.
Clean a whole list · MX lookup · SPF, DKIM and DMARC checker
Frequently asked questions
What is the difference between 550 and 554?
Both are permanent. 550 often points to the mailbox or policy, 554 is a broader transaction failure.
Is the mailbox bad?
Not necessarily. Many 554 errors are about the sender.
Other error codes
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