Status 5.1.1#
smtp;550 Invalid recipient <[email protected]> (#5.1.1)
The address does not exist, or is no longer active, at this provider.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.
Spam filter · 5.x.x permanent failure
Email Security.cloud SMTP 550 Errors: Every Bounce Response Explained
Every SMTP 550 response on record from Email Security.cloud, 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.
- Spam filter
- Email Security.cloud
- Code
- 550 (5xx)
- Responses
- 1
- Highest severity
- Unclassified
Email Security.cloud SMTP 550 responses
Email Security.cloud SMTP 550 questions
›What does an SMTP 550 error from Email Security.cloud 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 Email Security.cloud, 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 Email Security.cloud 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, and check Email Security.cloud's postmaster documentation.