I'm curious if anyone else has run into anything similar to this, I'm looking for a place to start investigating a little more thoroughly.
One of my clients is seeing their Exchange 2013 public folders stop working in Outlook. Users complain that Outlook says it can't open the public folders, and sometimes may just crash Outlook. Meanwhile we'll also notice queue buildups going to the PF database. Finally, we'll also notice that in EAC, the public folders view will be empty. Items in the queue to PF mailboxes will show the following error:
STOREDRV.Deliver.Exception:StorageTransientException.MapiExceptionTimeout; Failed to process message due to a transient exception with message Cannot open mailbox /o=Business/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=server/cn=Microsoft System Attendant. 16.55847:7E000000,
Then all of a sudden, the public folders are back, the queues will flush out, and the folder structure in EAC is back to normal. Usually seems like it's maybe somewhere between 10-30 minutes where it's unavailable. We're trying to map out the timing a little bit, see if we can find anything we can associate it with - we do know it came up a couple times while doing DB restore jobs, but it also came up when that's NOT been happening.
The database doesn't show it's dismounted in powershell, and the application log doesn't show any issues either. For all intents and purposes, everything looks fine. We've even mounted the DB on its DAG partner, but we've seen this come up again anyway.
My only suspicion is maybe it's related to a third party application blocking access for some reason, but I'm not sure why that would happen. That said, I don't want to rule out the possibility, so if anyone has any experience with that, I'd love to hear it.
And if anyone has any suggestions on where to search for clues, I'd also love to hear that. Thanks!