# SMTP: 554 5.4.14 Hop count exceeded - possible mail loop

**Code:** `554 5.4.14 Hop count exceeded - possible mail loop` · **Category:** Email / SMTP · **Seen on:** SMTP, Linux

The message passed through too many mail servers (usually over 25), which almost always means two systems forward mail to each other in a loop.

## Meaning

Each server adds a Received header. When the limit is reached the message bounces. Typical culprits are a forwarding rule on A to B and B back to A, a catch-all that forwards to itself, or an alias that points to its own address.

## Common causes

- Two forwarding rules pointing at each other
- Alias or forwarder pointing to itself
- Catch-all forwarding plus MX confusion
- Mail routing between on-prem and cloud misconfigured
- Auto-responders replying to each other

## Quick fix

1. Inspect the Received headers of the bounce to find the repeating hosts
2. Remove the circular forward or alias
3. Check MX records and accepted domains for conflicting routing

## Detailed fix by platform

### Postfix

1. `postconf -n | grep -E "virtual_alias|alias_maps"` and `postmap -q user@example.com hash:/etc/postfix/virtual` to see where an address goes

## How to diagnose

1. **Headers** — Which hosts repeat?
2. **Rules** — Forwarders pointing back?
3. **Routing** — MX and accepted domains?

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Source: [WhatIsMyError](https://whatismyerror.com/errors/email/554-5-4-14-hop-count-exceeded)