Forum Discussion
Email sent from Shared Mailbox gets stuck in Outbox
Hello,
I am working with a client who has a primary and shared mailbox in Outlook. They are using the newest version of classic Outlook desktop app and they have full permissions to the shared mailbox, including "send as" permissions. They can send email from their primary mailbox without issue. However, when they send email as the shared mailbox, it gets stuck in the Outbox and never sends. I have tried the following:
1. Removing the profiles re-adding
2. Deleting the Outlook data files
3. Reducing cache to as low as 3 months
4. Turning off cache but when I do the shared mailbox gets an error that it cannot connect to the Exchange server
5. Turning on auto-archive to shrink the data files
6. Switching to "New Outlook". This does seem to work but the company uses a plug-in for a program called "Mail Manager" and they don't fully support New Outlook yet
Sometimes these solutions will fix the issue for a few days to a week but then it begins happening again. This issue does not happen when they are using the mobile or web clients. To me this sounds like a corrupted data file but I can't pinpoint what exactly is causing the corruption.
Any suggestions?
Thanks,
Mike
5 Replies
i asked Copilot just now, and it confirms what i wrote above:
does this command 'Remove-MailboxPermission -ClearAutoMapping' achieve the same result as running 'Remove-MailboxPermission -AccessRights FullAccess' followed by 'Add-MailboxPermission AccessRights FullAccess -AutoMapping:$false'
Short answer:
Yes—using Remove-MailboxPermission -ClearAutoMapping achieves the same end state as removing a user’s FullAccess permission and then re‑adding it with -AutoMapping:$false. It clears the AutoMapping flag on the existing FullAccess ACE without removing the permission itself.- I am having the same issue and seeking a resolution. Like you, I thought I originally resolved this by removing data files and profiles within control panel > mail. I then re-added the primary account including shared mailbox. I was able to send as the shared mailbox for a few hours and prematurely celebrated.
Shortly after, I noticed that items are stuck in the outbox... and even stranger is that even though the profile and data files were removed, the outbox showed items stuck from before the data & profiles were removed. (they were not there when the accounts were re-added, but they came back somehow).armandsalmon Hey, so we managed to get this resolved using the solution below. Since we applied this, it's been 2 months without issue. I hope this helps you as well.
Resolution
The issue was resolved (with Microsoft support help) by re-applying Full Access permissions and removing shared mailbox Outlook auto-mapping for the affected users and then adding the shared mailbox manually in Outlook. Re-applying permission via Office 365 admin centre didn't have any effect.
- Launch Windows Power Shell as administrator and https://can01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.mysysadmintips.com%2Fwindows%2Fservers%2F373-connect-powershell-to-exchange-online-office-365&data=05%7C02%7CMike.Olejnik%40saultcollege.ca%7C3c662b4353344d1cd1ee08dcbbc281ec%7C9c61dd9d3b294f6db3b1f212de3c25da%7C0%7C0%7C638591691275807068%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C4000%7C%7C%7C&sdata=pd5Ecs6qk0h0J2zHahdvVayzK8783b0rqeMqOxGXYXc%3D&reserved=0.
- Run: Remove-MailboxPermission -Identity mailto:email address removed for privacy reasons -User mailto:email address removed for privacy reasons -AccessRights FullAccess
- Run: Add-MailboxPermission -Identity mailto:email address removed for privacy reasons -User mailto:email address removed for privacy reasons -AccessRights FullAccess -AutoMapping:$false
- -AutoMapping:$false disables shared mailbox auto-mapping to users' Outlook profiles.
- Wait 30-60 minutes for changes to propagate until shared mailbox disappear from users' Outlook.
- Manually add shared mailbox to users' Outlook: File > Account Settings > Change > More Settings > Advanced > Open these additional mailboxes.
- Try sending email as the shared mailbox by selecting From: address from Online Global Address List (to prevent caching issues).
Looks like they have improved the commandlet and you can achieve the same by doing this instead:
Remove-MailboxPermission -Identity "HR Project" -ClearAutoMapping
In Exchange Online, this example excludes the HR Project mailbox from auto-mapping in Outlook for all users who have Full Access permission to the mailbox.
