Free tool

Translate an email bounce

“550 5.7.26 Unauthenticated email is not accepted.” Got one of those cryptic messages? Paste it: we tell you what happened, whether it is temporary, and what to do.

Examples

🔒 The message is analyzed in your browser; it is not sent anywhere.

Temporary or permanent: the first digit says it all

4xx · 4.x.x

Temporary

The recipient’s server said “not now”. Yours keeps trying on its own, usually for one to five days. You may receive a “delayed” warning in the meantime.

Do not resend: wait for success or a final failure.

5xx · 5.x.x

Permanent

The server said “no”. Nothing will be retried. Resending the same message the same way will give the same result.

Fix the cause, then resend.

The extended code (three numbers separated by dots, like 5.7.26) gives the category: x.1 address, x.2 mailbox, x.3 mail system, x.4 network and routing, x.5 protocol, x.6 content, x.7 security or policy. Providers such as Google and Microsoft then add their own numbers.

Who needs to act?

You

The address or the message

Typo, address closed, file too large, sending limit reached, wrong password in your software.

Most bounces are fixed here.

Your provider

Your domain or your server

SPF, DKIM or DMARC missing, server on a blacklist, account blocked for spam.

Our SPF, DKIM & DMARC checker and blacklist check show what to fix.

The recipient

Their side

Mailbox full, account disabled, group restricted, server down or misconfigured.

Reach them another way (phone, text).

If many of your messages bounce

  1. Check your authenticationSince 2024, Gmail, Yahoo and Microsoft refuse more and more mail without SPF, DKIM and DMARC. Start with our checker.
  2. Send yourself a real testOur live email test shows how a message from your account actually arrives.
  3. Make sure your account is not hackedSudden blacklisting or a blocked account often means someone is sending spam with your password.

Is the bounce itself suspicious (you never sent that message)? Spammers forge sender addresses: this “backscatter” is annoying but harmless. A strict DMARC policy on your domain makes it rarer. And if it contains a link asking you to “release” messages, analyze it with our email header analyzer before clicking.