Email bounce errors explained

Gmail and Outlook now reject mail that is not authenticated. Paste your bounce message to see what it means and how to fix it.

Common authentication errors

• Gmail 550 5.7.26 – “sender is unauthenticated” / DMARC policy
• Gmail 421 4.7.26 – “rate limited because it is unauthenticated”
• Gmail 550 5.7.27 / 421 4.7.27 – message didn't pass SPF authentication
• Gmail 550 5.7.30 / 421 4.7.30 – message didn't pass DKIM authentication
• Gmail 550 5.7.32 / 421 4.7.32 – From header not aligned with SPF or DKIM
• Gmail 550 5.7.40 / 421 4.7.40 – no DMARC record for the sending domain
• Gmail 550 5.7.24 / 421 4.7.24 – suspicious entries in your SPF record
• Gmail 550 5.7.25 / 421 4.7.23 – sending IP has no PTR (reverse DNS) record
• Gmail 550 5.7.29 / 421 4.7.29 – message not sent over a TLS connection
• Outlook / Hotmail 550 5.7.515 – domain does not meet the required authentication level

Check your domain