Dat is een bekend probleem met IMAP accounts, meen ik me te herinneren....
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Zie verder: https://www.msoutlook.info/question/291
Icon doesn’t reflect the status
If the icon has been added but it does not show the reply or forward status, then there could be various reasons why this is happening. The most common ones;
- You replied to a message which was using a custom form;
There is no solution for this.
- You have a virus scanner that integrates with Outlook which is causing some nastiness;
Disable or uninstall this integration and try again;
- You have an add-in installed which does something to special to a message;
See if it works correctly in Outlook Safe Mode or when you disable all your add-ins.
- The message has been replied to or forwarded with a mobile device;
Not all devices or sync applications support syncing the forward/reply status as well.
- If you are using Exchange or the Outlook Connector you could be experiencing sync issues between Outlook and the mail server.
Check the Sync Issues folder for any reports or items that experienced issues.