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Mailbox troubleshooting · Practical guide

IMAP duplicate message handling: distinguish duplicate fetches from duplicate mail

Compare mailbox identity and Message-ID before deleting records or replaying a synchronization window.

Reviewed · Examples are illustrative

Who this helps: Mailbox owners and administrators validating sending and reply access.

Define the decision

Zintara checks an inbound message’s nonempty RFC Message-ID within the connected mailbox before inserting it again. This helps with repeated fetches, but it is not a universal exactly-once guarantee for missing or rewritten identifiers.

Work through the procedure

  1. Preserve both apparent duplicates and their raw identifiers.
  2. Check whether they belong to the same connected mailbox.
  3. Compare Message-ID, In-Reply-To, receipt time and provider folder.
  4. Determine whether the provider delivered two messages or the application repeated processing.

Worked example

The following is a synthetic example for this procedure, not a customer result or performance benchmark.

Copy A: mailbox X, Message-ID <[email protected]>
Copy B: mailbox X, same Message-ID
Expected reviewed path: existing inbound message recognized
Different mailbox or missing ID: requires separate investigation

Read the result

The identity comparison prevents deleting a legitimate second reply merely because its subject and body look similar. Subject text alone is not a reliable deduplication key.

Check before moving on

  1. Check whether forwarding rewrote identifiers.
  2. Record sync errors around the duplicate observation.

Limits and next action

Avoid direct database deletion as the first fix. Use an operator-reviewed correction after establishing the source and preserve an audit trail for any changed records.

Source: RFC 9051: mailbox identity and synchronization context

Source references

Worked examples are illustrative. Editorial procedures are suggested methods, not measured performance claims or promises of additional product features. Check current provider guidance before changing mailbox configuration.

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