Gmail 550 5.7.27: message didn't pass SPF authentication

What the bounce means and the exact steps to stop it.

The bounce looks like this
550-5.7.27 This message was blocked because it didn't pass SPF authentication.
421-4.7.27 Your email has been rate limited because SPF authentication didn't pass for this message.

What it means

Gmail requires bulk senders to pass SPF. The server that sent this message is not listed in the SPF record of the envelope (Return-Path) domain, the record has a syntax error, or it needs more than 10 DNS lookups and is treated as broken.

How to fix it

  1. Run the checker: it counts SPF DNS lookups including nested includes.
  2. Add the missing sender with the SPF generator and replace (not add) your SPF record – two SPF records also fail.
  3. Over 10 lookups? Remove services you no longer use or replace broad includes with the provider's narrower one.
  4. If you send through a service that uses its own Return-Path domain, set up its custom return-path/bounce domain so SPF passes for your domain.

Check your domain now

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Prefer to do it yourself? Get the step-by-step Fix Kit ($15) – 19-page guide, checklist, 20+ providers.

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