554 5.4.6: mail loop detected
The message passed through more than 50 mail servers on its way, which usually means it is stuck in a loop, so Gmail stopped it.
- Gmail
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 554 5.4.6
- Provider
- Gmail and Google Workspace
- Temporary or permanent
- PermanentRefused for good: the message comes back to the sender, and resending it gets the same answer.
- Who has to act
- The sender. The fix is on the sending side: your domain, your server or your list.
- What the server says
554 5.4.6 Message exceeded 50 hops…
What it means
Every server that handles a message adds a Received header. When a message has passed through more than 50 mail server hops, Gmail assumes it is going round in circles and rejects it. Google's relay documentation lists the usual loops: Workspace mail routed to an outside gateway that sends it back through smtp-relay.gmail.com, routing or compliance rules that send mail back to where it came from, and forwarding rules or automatic replies that pass messages between mailboxes, groups or aliases. The Received headers in the bounce show which servers repeat.
Common causes
- Workspace mail routed to a gateway that relays it back through smtp-relay.gmail.com.
- Routing or content compliance rules that send mail back to the gateway it came from.
- Forwarding rules or automatic replies between mailboxes, groups or aliases that point at each other.
- Two servers whose smart host settings each hand the message to the other.
How to fix it
- 01Read the Received headers of the bounced message, or trace it in Email Log Search, to find the servers that repeat.
- 02Do not route Gmail-originated mail to a gateway that relays it back through smtp-relay.gmail.com.
- 03Make routing rules that send to an outside gateway exclude mail already arriving from that gateway.
- 04Check the mailboxes, groups and aliases involved for forwarding or automatic replies that point at each other.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- Gmail SMTP errors and codes (Google Workspace Admin Help)knowledge.workspace.google.com
- SMTP relay service error messages (Google Workspace Admin Help)knowledge.workspace.google.com
Related codes
- 554Transaction failed.The server permanently refused the transaction, often after receiving the message data or straight away when the connection opened.
- 5.4.6Mail routing loop.The message was passed back and forth between servers, or forwarded around a circle, until a server noticed the loop and stopped it.
Further reading
All 108 Gmail codesEvery code in the wikiPaste your own bounce