554 5.4.6 Gmail bounce: mail loop detected
What 554 5.4.6 means
The message passed through more than 50 mail hops, which Gmail treats as a routing loop.
Message text
Message exceeded 50 hops, this may show a mail loop…
This is an excerpt: the provider's documentation shortens the message. Full text: provider documentation
Common causes of 554 5.4.6
- Forwarding or routing configuration sends mail back into itself
- Mail loop between two servers
How to fix 554 5.4.6
- Check forwarding rules and routing configuration for a loop.
- Confirm where the domain delivers mail with MX lookup.
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How to read 554 5.4.6
The first part, 554, is the SMTP reply code. Transaction failed: a general permanent failure, often a policy or reputation block. Replies that start with 4 are temporary and replies that start with 5 are permanent (RFC 5321 §4.2.1).
The second part, 5.4.6, 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 4 is network and routing: a problem reaching or routing to the destination. 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
- How to set up MX records (priorities, null MX, migration)
- MX host does not resolve: causes and how to fix it
- Null MX (RFC 7505): publish it for domains with no mail
Related codes
- 5.4.4 SMTP: unable to route
- 5.4.1 Microsoft: relay access denied
- 5.4.1 Microsoft: recipient rejected
- 5.4.14 Microsoft: routing loop
- 5.4.300 Microsoft: not delivered in time
- 5.4.8 Microsoft: mx not in mta-sts policy
FAQ
What does 554 5.4.6 mean?
The message passed through more than 50 mail hops, which Gmail treats as a routing loop. This is a permanent failure.
How do I fix 554 5.4.6?
Check forwarding rules and routing configuration for a loop. Confirm where the domain delivers mail with MX lookup.
Is 554 5.4.6 permanent, and should I retry?
554 5.4.6 is a permanent failure, so retrying the same message will fail again. Fix the cause first, then send a new message.