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553 5.1.2 Recipient domain not found

permanent Hard Bounce

Meaning

The receiving server could not find the domain part of the recipient's email address.

Common causes

  • The email address contains a typo in the domain name.
  • The domain no longer exists or its DNS records are missing.

How to fix

  1. Remove the address from your active mailing list.
  2. Check for obvious typos and correct them if possible.
  3. Implement email validation at signup.

Provider notes

Gmail. Explicitly states 'We weren't able to find the recipient domain. Please check for any spelling errors...'

Example bounce

553 5.1.2 We weren't able to find the recipient domain.

FAQ

How is this different from 550 5.1.2?
They mean the exact same thing. Different mail servers (like Gmail) prefer using the 553 reply code for invalid recipient syntax/routing.

Related codes