Status 5.7.1#
smtp;550 5.7.1 Rejected by spam filter (in reply to end of DATA command)
The receiver refused the message for good and points at a policy or security problem (enhanced status 5.7.1). Use the wording above to pin down the exact fix.
Email provider · 5.x.x permanent failure
ProtonMail SMTP 550 Errors: Every Bounce Response Explained
Every SMTP 550 response on record from ProtonMail, with the verbatim text, the enhanced status code, a severity rating and a plain-English fix.
The mailbox is unavailable and the message is rejected for good. This is the catch-all permanent failure, covering everything from an unknown address to an authentication failure to a reputation block, so the wording after the number is what actually tells you the reason.
- Provider
- ProtonMail
- Code
- 550 (5xx)
- Responses
- 1
- Highest severity
- Unclassified
ProtonMail SMTP 550 responses
ProtonMail SMTP 550 questions
›What does an SMTP 550 error from ProtonMail mean?
The mailbox is unavailable and the message is rejected for good. This is the catch-all permanent failure, covering everything from an unknown address to an authentication failure to a reputation block, so the wording after the number is what actually tells you the reason. At ProtonMail, it is a permanent rejection, and the specific reason is in the enhanced status code and message text of each response below.
›How do I stop ProtonMail from returning SMTP 550?
Match your bounce text to one of the responses below and follow its guidance. Recipient-side wording means fix the address. Authentication or reputation wording (SPF, DKIM, DMARC, blocklist) means fix your sending setup.