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Using Microsoft Outlook version 2201 (Preview Channel) I get the same error on two different computers when I use Reply All:
The operation failed. The messaging interfaces have returned an unknown error. If the problem persists, restart Oulook.
I already tried to restart outlook, change profile, create another profile, but the error continues.
Creating a new profile I also created a new .OST file, so I would exclude that the issue is a corrupt file.
The error does not show when I am connected to a personal Hotmail account. The error only shows up on my work account.
Because it happens now on two different computers (desktop and notebook) it does not seem something corrupted at the PC level.
Additional note: also ReplyAll from VBA (using Outlook.MailItem) failed, in that case without showing the dialog box UI.
The Reply and Forward buttons and corresponding VBA commands work regularly.
I also monitored with Process Explorer to see whether there are errors accessing Registry or File System, but I didn't see any particular error when I click "Reply All".
In the Event Viewer I have this entry in the Microsoft Office Alerts:
Microsoft Outlook
The operation failed. The messaging interfaces have returned an unknown error. If the problem persists, restart Outlook.
P1: 301670
P2: 16.0.14827.20186
P3:
P4: 0x80004005
My only suspect at this point is that there is something that happens with version 2201, but I don't know how to get more details about the error to investigate deeper. Any help would be welcome.
Using Classic Outlook on Windows for personal email, calendar, and contact management
Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.
Thanks for sharing your findings, George. I went back to the original bug for this issue and it shows fixed in build 15310.10000. That matches your observations.
The fix should go to Current Channel ~May 27, 2022 via Version 2006 15330.xxxxx.
This problem has disappeared on one of my two computers with the latest release of Office build 15330.20114.
It still fails on my other computer that is on Build 15225.20288.
I kept putting off trying to create new Outlook profiles on my two computers, and from March to now, every time I needed to reply all, I have been manually copying the various email addresses. As tedious as that has been I didn't have to rebuild my Outlook Rules, which never seem to be quire right when i save and restore them.
I solved this issue by creating an email distribution group with my primary email as a member and adding all my aliases as email addresses for that group and removing the aliases from my primary mailbox