Email provider · 5.x.x permanent failure
Every SMTP 550 response on record from Free, 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.
smtp;550 spam detected
The receiver refused this message outright and will not accept an unchanged retry. The wording above is the only clue to what needs to change, most often the address, authentication, or sending reputation.
Provider documentation
smtp;550 5.2.2 user quota exceeded
The recipient's mailbox is full or over its storage limit. There is nothing to fix on the sending side; delivery may succeed later once they clear space.
Provider documentation
smtp;550 5.2.1 This mailbox has been blocked due to inactivity
The address does not exist, or is no longer active, at this provider. Remove it from your list and check for a typo in the local part or the domain.
Provider documentation
smtp;550 virus detected
The receiver flagged the message as carrying a virus, malware, or a phishing payload. Rebuild it from a clean source and scan every attachment and link before you resend.
Provider documentation
Postmaster & documentation
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 Free, it is a permanent rejection, and the specific reason is in the enhanced status code and message text of each response below.
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, and check Free's postmaster documentation.
