553 5.1.2 Gmail bounce: recipient domain not found
What 553 5.1.2 means
Gmail could not find the recipient domain, so the address cannot be delivered to.
Message text
We weren't able to find the recipient domain…
This is an excerpt: the provider's documentation shortens the message. Full text: provider documentation
Common causes of 553 5.1.2
- Misspelt recipient domain
- Recipient domain has no mail server records
How to fix 553 5.1.2
- Check the recipient domain spelling and punctuation.
- Check the recipient domain publishes MX records with MX lookup.
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How to read 553 5.1.2
The first part, 553, is the SMTP reply code. Requested action not taken, mailbox name not allowed: the mailbox address is malformed or not permitted. Replies that start with 4 are temporary and replies that start with 5 are permanent (RFC 5321 §4.2.1).
The second part, 5.1.2, is an enhanced status code (RFC 3463 §2) written class.subject.detail. Class 5 is a Permanent failure (5xx): the command was rejected and the sender should not repeat it unchanged (RFC 5321 §4.2.1; RFC 3463 §2).. Subject 1 is addressing: a problem with the recipient or sender address. The detail number refines the subject, and providers may define details of their own, which is why one code can read differently at Gmail, Microsoft and Yahoo.
Do not keep resending the same message: a permanent failure repeats until the cause is fixed. Correct the cause, then send a new message.
Official source: knowledge.workspace.google.com. Last verified 2026-10-20.
Related guides
- MX host does not resolve: causes and how to fix it
- How to set up MX records (priorities, null MX, migration)
- MX record points to a CNAME: why it breaks and the fix
Related codes
- 5.1.2 SMTP: bad destination system
- 5.1.1 SMTP: bad destination mailbox
- 5.1.3 SMTP: bad address syntax
- 5.1.10 SMTP: recipient has null MX
- 550 5.1.1 Microsoft: bad mailbox address
- 550 5.1.10 Microsoft: recipient not found
FAQ
What does 553 5.1.2 mean?
Gmail could not find the recipient domain, so the address cannot be delivered to. This is a permanent failure.
How do I fix 553 5.1.2?
Check the recipient domain spelling and punctuation. Check the recipient domain publishes MX records with MX lookup.
Is 553 5.1.2 permanent, and should I retry?
553 5.1.2 is a permanent failure, so retrying the same message will fail again. Fix the cause first, then send a new message.