Confirm this is a forwarding-chain problem
Map each authorised forwarder until an address repeats, then remove the returning edge while keeping loop protection enabled.
A saved forwarder error or authorised delivery report may reveal a cycle among addresses you control. Map only rules their owners may inspect; DirectAdmin forwarding depends on the purchased service. If an external owner holds part of the chain, request their help rather than opening another mailbox or disabling loop checks.
A loop is different from one message being rejected for spam, sender authentication or quota. Preserve the actual error text, affected sender and recipient addresses, approximate time and a message identifier if available. Redact message content and personal addresses when seeking general help. Do not assume every recipient failed: DirectAdmin’s later Exim change describes a configuration that discards a loop while continuing delivery to other recipients, whereas older behaviour could bounce.
Find the first returning forwarding rule
List each forwarder you are authorised to see as a source-to-destination arrow. For example, team@example.com may forward to a second address that routes back through an alias to team@example.com. These are example names, not Novasean mailboxes. Include application aliases and external-provider forwarding only where their owners can confirm them. A single forwarder panel may show only one edge of a cycle.
Read the chain in order and find the first edge that returns a message to an address already visited. DirectAdmin documents a local anti-loop check when creating forwarders, but that is version and configuration evidence, not a guarantee that a cross-provider cycle will be shown in your panel. If the error gives a chain, compare it with the actual configured addresses rather than assuming the displayed order covers every remote hop.
Choose a non-cyclic destination with its owner
Decide where the message should finally be delivered: an authorised mailbox, an agreed group address or a provider-approved route. Confirm that the final address does not forward back to an earlier node. Save the old forwarder values before any change, and arrange a test sender and recipient who consent to the check. Avoid using a live customer conversation as a test message.
At the control you own, replace or remove only the returning forwarder edge. If the loop passes through an external service, its owner must make that change. Do not disable anti-loop checks, edit Exim, create a catch-all to mask the problem or change MX records for an account-level forwarding cycle.
Test final delivery and remaining recipients
Send a fresh, harmless message from an authorised external sender to the original address. Check that the intended final mailbox receives one copy and that the sender does not receive a loop report. If the rule has several legitimate recipients, test the ones you control separately; a lack of bounce alone does not prove they all received mail. Note the time and message identifier for any support handoff.
For team@example.com → desk@example.com → team@example.com, removing the second returning rule should leave one delivery to the chosen final mailbox in a fresh controlled test.
If the cycle persists, stop adding aliases and ask the owner of the unknown edge or the mail operator to trace the accepted message through available logs. Give them the mapped chain and observed result, not mailbox passwords. If legitimate delivery was broken by the new route, restore the saved previous forwarder only after checking it will not recreate the cycle; otherwise ask the operator for a safe temporary destination.
Frequently asked questions
Will a loop always bounce the whole message? No universal outcome follows from the symptom. DirectAdmin documents different behaviour across Exim configurations and versions.
Can I fix it by turning off loop protection? No. Correct the returning route while leaving protection in place.
What if I control only one address? Share the minimal chain and error with the other authorised owner or support. Do not guess at their forwarding rules.
Does one delivered test prove every recipient is reached? No. Check each authorised destination that the rule is meant to serve.
Sources and technical references
Related guides
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