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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.
Same issue on Windows 10 Pro 21H2 build 19044.1466 & Outlook Version 2202 (Build 14931.20010 Click-to-Run)
Attempted
This is also happening with other users in our organization.
I wrote out the steps here to resolve this issue if anyone is interested.
http://ctobob.com/2022/04/07/outlook-365-reply-all-not-working/
My Reply All issue is 100% whenever I click the reply all button and when clicking on suggestions.
I have three accounts connected to my Outlook:
1 - Office 365 primary account - Reply All does not work.
2 - Office 365 an additional account - Reply All Works
Both the Office 365 are in my same subscription just different domains.
Hi Marco,
Greetings.
Thank you for raising your concern in this community.
Could please check the update version Update history for Microsoft 365 Apps (listed by date) - Office release notes | Microsoft Docs
I am on current channel and this is the latest update.
You mentioned using a preview, could you please share a full screenshot just as in the picture above.
I am assuming that you are in Semi-Annual Enterprise as it actually the one with a previous, however, it does not have the 2201 version.
Please first check the link and see if you can try another update, and if you are still facing the same issue, please check using outlook on the web to see how it goes https://outlook.office.com/
I will be waiting for your feedback for further assistance.
Kind regards,
Mac