One of the shared mailboxes in my customer organization has stopped allowing new Outlook connections. The organization uses a local Exchange 2013 server. The mailbox is called *** Email address is removed for privacy ***, and several users open the mailbox in Outlook, both 2010 and 2016. It has been working fine until 2 days ago when it showed up as disconnected in one user. Nothing I did allowed it to connect, and when I tried to remove the mailbox and re-add it, the process failed. I also can no longer configure the mailbox in Outlook on any other machine - I've tried a mix of Windows 7 and 10, Outlook 2010 and 2016. I logged into 2 unused computers, one of them a brand new Windows 10 box, as the actual verify user, and still can't load the mailbox. The error I get in Outlook 2016 is:
- Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The attempt to log on to Microsoft Exchange has failed.
If I try to create a profile to the mailbox in Outlook 2010, the error is:
- The action cannot be completed. The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action.
I've tried a lot of the standard steps I see in other articles, like safe mode and resetnavpane, but those didn't help - not unexpected since this is a problem on multiple different machines and versions of Outlook. Of particular note are two things:
- All the other users that have this mailbox configured in Outlook have not experienced a problem - the mailbox is still connected and receiving mail.
- I can log into the mailbox with no problem using OWA
The other night I rebooted the domain controller. This seemed to fix the problem - but only for a few hours. I was able to create an Outlook profile that night, and the affected user was connected, but by the next morning it was failing again, and the user was disconnected. Last night I rebooted the Exchange server to similar results - it worked last night, but once again this morning I cannot create a new profile for that mailbox.
So I'm at a loss. None of the standard suggestions seem to work - does anyone recognize this problem?
Update 09/16/19: I thought I had fixed the problem on Friday night by adding more space to the database drive - that drive was a little under 10% free, so I got it above that. I tried adding the mailbox to my test machine and was successful, I then tested the machine showing as disconnected and it connected fine. I tested all weekend, and finally on Sunday afternoon I successfully added the mailbox to another client. It all seemed to work fine. However, it's now Monday morning, and I went back to my test machine - it's failing again, with all the same errors as above.
This doesn't make sense - how could it work all weekend, but start failing Monday morning? The only correlation I see is the users coming in and working in Outlook. I had everyone close Outlook over the weekend, now everyone will have it running - is it possible one of the existing Outlook clients could be causing this behavior somehow?