450: recipient is receiving too fast

What it means

These two cases protect a single mailbox rather than the platform. In case r1801, too many delivery attempts to the same recipient were running in parallel; in case r0403, the recipient address was contacted too often within a certain period. Either way GMX answers with a temporary 450 and the message stays in your queue. GMX says no manual action is needed: once the burst is over, the retry is delivered. It is worth a look only if one address gets this regularly, which suggests a loop, a script or a notification system sending to it too often.

Common causes

• Many messages to one GMX address were sent at the same time.
• An automated system sends notifications to the same recipient in quick succession.
• A forwarding rule or loop delivers copies of the same mail repeatedly.

How to fix it

1. 01Let your server retry; GMX expects the next attempt to succeed.
2. 02If one address is affected regularly, find the system that writes to it so often and batch or slow it down.
3. 03Check for forwarding loops that keep resending to the address.

Sources

What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.

• GMX Postmaster case r1801: 450 Reject due to policy violationspostmaster.gmx.net
• GMX Postmaster case r0403: 450 Reject due to policy violationspostmaster.gmx.net