What are the common email error codes and their meanings?

• Error 421 – Service not available, closing transmission channel
  • Meaning: Temporary server issue.
  • Resolution: Try resending later. If persistent, contact support@ipserverone.com to ensure the server is working.

• Error 450 – Requested mail action not taken: mailbox unavailable
  • Meaning: The recipient’s mailbox is either full or temporarily unavailable.
  • Resolution: Contact the recipient or wait for their mailbox to become available.

• Error 451 – Requested action aborted: local error in processing
  • Meaning: A temporary server issue at the recipient’s end.
  • Resolution: Wait and try sending again later.

• Error 550 – Requested action not taken: mailbox unavailable
  • Meaning: The recipient’s mailbox doesn’t exist, or the server is rejecting the email.
  • Resolution: Double-check the recipient’s email address or confirm if the domain is valid.

• Error 552 – Requested mail action aborted: exceeded storage allocation
  • Meaning: The recipient’s mailbox has exceeded its storage limit.
  • Resolution: Contact the recipient to clear their mailbox.

• Error 554 – Transaction failed
  • Meaning: The email is blocked, often due to spam or blacklisting issues.
  • Resolution: Verify SPF, DKIM, and DMARC settings. Check if your domain is blacklisted and request removal.