421 4.7.26: Rate limited because unauthenticated (Gmail)
Gmail is delaying your mail because it doesn't pass SPF or DKIM. If it continues, it may turn into a 550 5.7.26 rejection.
Temporary Often fixes itself or after a small change. Your server may retry.
What the bounce message looks like
The wording changes from one provider to another. These are typical examples:
421-4.7.26 This mail has been rate limited because it is unauthenticated. Gmail requires all senders to authenticate with either SPF or DKIM.Common causes
- No SPF record, or your sending service isn't in it
- DKIM signing isn't turned on
How to fix it if you sent the email
- Set up SPF and DKIM. Use the SPF generator and check with the DMARC checker.
If you manage the receiving or sending mail system
- Turn on DKIM signing in your email platform.
Free tool: paste the full bounce into the bounce message decoder to get a plain-English reading of every code in it.
Questions people ask
- What does 421 4.7.26 mean?
- Gmail is delaying your mail because it doesn't pass SPF or DKIM. If it continues, it may turn into a 550 5.7.26 rejection.
- Is 421 4.7.26 a hard or soft bounce?
- Temporary. Often fixes itself or after a small change. Your server may retry.
- Should I remove the address after a 4.7.26 bounce?
- Not straight away. Retry later, and remove it only if it keeps failing for weeks.