Copy the current global and mailbox filter rules before editing. Prepare a harmless sample that reproduces the problem, including relevant headers, and protect any private message content.

1. Open Global Email Filters to inspect account-wide rules, then Email Filters for the affected mailbox.
2. Read each rule’s conditions and actions in sequence. Look for broad matches, redirects, discards and actions that stop processing.
3. Use the available filter test with representative message content. Check which conditions match rather than assuming the subject is the only relevant field.
4. Reorder or narrow the specific conflicting rule. Make one change at a time and save the intended sequence.
5. Send a real external test that should match and another that should not. Check Inbox, destination folders, forwarders and Track Delivery for the final behaviour.

The matching message should receive the intended action without affecting unrelated mail. A redirection action does not automatically mean a second local copy will be retained.

If test output differs from real delivery, inspect global rules, spam handling, recipient routing and the actual headers available to the filter. BCC recipients are not reliably represented as an ordinary visible message header. Restore the saved rule order if the change causes wider delivery problems.

Separate narrowly defined rules are often easier to test and maintain. Name each rule by its purpose and document why its position matters, especially before a discard or stop-processing action.

• Using plus addressing to organise incoming cPanel email
• Tracing a missing message with cPanel Track Delivery
• Why does forwarded mail fail when direct delivery works?
• Changing an email mailbox password in cPanel

• cPanel: Global Email Filters
• cPanel: Email Filters
• cPanel: How To Configure Email Filters