Forum Discussion
Edited Netaddress Email Keeps Duplicating
In Outlook 2016 I have two IMAP accounts, one to exchange server that allows a read email subject line to be edited then saved without problem. The other is to a Netaddress email server. When I follow the same edit and save procedure in a Netaddress email it duplicates over and over, the only way to stop it is to close Outlook. So is this an undesirable feature of Outlook or is it a Netaddress problem or both?
2 Replies
The reason why the editing is needed is to make sense of the list of received emails in the inbox, for example P-a-y-P-a-l send spend emails but do not mention the amount in the subject line.
The fix given by Netaddress says:
"As for the issue, what you're describing is a known issue with Outlook 2016 and IMAP accounts. Unlike POP or Exchange, IMAP treats most message properties as synchronized server items. When you edit the subject of an existing email, Outlook effectively creates a modified version of the message and tries to re-sync it with the IMAP server. Some IMAP servers do not handle this properly and can continually re-upload or re-synchronize the message, resulting in duplicate copies."
But an AI gave more in depth detail:
Your understanding is correct: a standard IMAP server and Microsoft Exchange behave very differently in this specific scenario.
- Standard IMAP and the "Delete & Re-Create" Approach: When an email client (like Outlook) edits the subject line of an email on a standard IMAP server, it is fundamentally changing a core part of the message. To achieve this, the standard IMAP protocol essentially requires the client to delete the original message and upload a completely new one with the changed subject. This creates a new, distinct email on the server, which often leads to duplicates if the client or server gets confused in the process.
- Exchange Server and the "In-Place Update": Your Exchange server, however, doesn't rely on this same limitation. Exchange has a more advanced architecture and interacts with clients (like Outlook) using the MAPI protocol. Through this, when you edit the subject in Outlook, it can directly modify the existing item on the server. The email is not deleted and recreated; it is simply updated in-place. This is why it never triggers the duplicate loop you see with your other IMAP server. The server sees it as the same message being changed, not a new one being uploaded.
All I can do is follow Netaddress supports advice and take it from there.
The behavior between the Exchange and Netaddress accounts indicates an IMAP server or synchronization interaction, not an Outlook feature. Editing a received message changes the stored item; with IMAP, Outlook must synchronize that replacement to the provider. If Netaddress does not handle that operation consistently, each synchronization can create another copy. Stop editing messages in that mailbox until testing is complete. Update Outlook, create a new Outlook profile containing only the Netaddress account, and reproduce with one harmless test message. Compare the same edit in Netaddress webmail. If duplication occurs there, the provider owns the behavior; if it occurs only in Outlook, collect a synchronization log and contact Microsoft support. Office and Outlook 2016 reached end of support in October 2025, so Microsoft no longer supplies bug or security fixes. The safest long-term step is moving to a supported Outlook version. Use categories or flags instead of editing received subjects.
