Bounce Codes
554 5.4.6 Permanent Failure Routing loop detected (too many hops)
The message bounced between mail servers too many times (often due to conflicting forwarding rules) and was permanently rejected to prevent an infinite loop.
Common causes
- Two mail servers each forwarding to the other for the same address.
- Misconfigured auto-forwarding rule creating a cycle.
What to do
This is a mail-routing configuration issue, typically on the recipient domain's side, rather than anything the sender can fix. Suppress if persistent and, if a direct relationship exists, flag it to the recipient's IT team.
FAQ
Is this a common bounce type?
No — it's one of the rarer bounce codes, generally only appearing when a domain's own forwarding configuration is broken rather than anything related to how the message was sent.
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