Error Description
SMTP error 455 is a permanent or "5xx" error code returned by a mail server to indicate that it has encountered a specific policy violation or other reasons that lead to the rejection of an incoming email message. Unlike transient errors, SMTP error 455 suggests that the issue is not temporary and is unlikely to be resolved without addressing the underlying problem.
What's Causing This Error?
SMTP error 455 can be caused by various reasons, including::
- Content policy violations: The email message contains content that clearly violates the recipient server's policies, such as spam, malware, or prohibited file types.
- Sender reputation issues: The sender's email address or domain has a poor reputation, possibly due to previous policy violations or spammy behavior.
- Invalid recipient address: The recipient's email address provided in the "RCPT TO" command or the "To:" field of the email message does not correspond to a valid email account or mailbox.
How to fix SMTP Error 455?
- Review email content: Ensure that the email message content complies with the recipient server's policies. Remove or modify any content that may be flagged as spam or malicious.
- Improve sender reputation: Address any issues related to the sender's reputation by adhering to email best practices and policies. Avoid sending spam or engaging in spammy behavior.
- Verify recipient address: Ensure that the recipient's email address is spelled correctly, is complete, and corresponds to a valid email account or mailbox.
SMTP Error 455 Examples
Example 1: "455 5.7.1 Content blocked due to policy violations. Email flagged as spam."
Example 2: "455 5.1.0 Sender's domain blacklisted for abusive behavior. Contact administrator for removal."
Example 3: "455 5.5.2 Invalid recipient address recipient@example.com. Check recipient details."
