Exchange 2010 error 9646?

Question

Microsoft Exchange

There are 2 exchange 2010 (dag) servers, recently errors 9646 "exceeded the maximum number of objects of the type "objtFolder" (1000)" began to pour
. some only have their own account.
As you can see from the error - I increased the limit from the default 500 to 1000 - it didn’t help, right away errors began to pour already with the limit exceeded by 1k.
I rebooted the server - it didn’t help. I
rummaged through the whole google, basically they advise to increase the limits or to find out why the user has such garbage, but since the limits did not help, and the users are completely random (so far the connection is not clear), then I'm at an impasse.
Hence a couple of questions - is it possible to see with some command from which IPs these same objtfolders are open in a specific account?
Could it be some kind of virus?

Answer 1

Take a "random" user and look at get-mailboxfolderstatistics to see how many objects, folders, etc. they have. Perhaps he did them just an overdofiga, and also an outlook online, I suppose, because it’s more convenient for him.
The second variant is possible that the user has just overmapped mailboxes and he makes just a cosmic number of simultaneous MAPI sessions.

Answer 2

Get-MailboxFolderStatistics -Identity $mailbox | ft -a name, foldertype, foldersize, itemsinfolder
Well, if this command is used to screw up the user's box about which this error is being reported:
Root storage level Root 0 B (0 bytes) 0
Conversation Action Settings ConversationActions 0 B (0 bytes) 0
RSS feeds RssSubscription 0 B (0 bytes) 0
Inbox Inbox 12.57 GB (13,501,409,538 bytes) 70234
possibly spam User-created 0 B (0 bytes) 0
Diary Journal 0 B (0 bytes) 0
Tasks Tasks 295 B (295 bytes) 1
Notes Notes 0 B (0 bytes) 0
Outbox Outbox 220.5 KB (225,832 bytes) 13
Calendar Calendar 2.134 MB (2,237,621 bytes) 100
Contacts Contacts 48.25 KB ( 49,404 bytes) 14
Customize Quick Actions User Created 1.117 KB (1,144 bytes) 1
Junk Mail JunkEmail 12.38 MB (12,979,545 bytes) 116
Sent SentItems 4.652 GB (4,995,328,805 bytes)
11857 Synchronization errors SyncIssues 0 B (0 bytes) 0
Conflicts Conflicts 1.002 GB (1,075,483,681 bytes) 4952
Local Error LocalFailures 0 B (0 bytes) 0
Server Errors ServerFailures 0 B (0 bytes) 0
Newsletter Created by user 0 B (0 bytes) 0
Proposed contacts created User 0 B (0 bytes) 0
Deleted DeletedItems 74.95 MB (78,593,166 bytes) 788
Drafts Drafts 192.6 KB (197,192 bytes) 4
Recoverable Items RecoverableItemsRoot 196.2 KB (200,907 bytes )71
Deletions RecoverableItemsDeletions 3.204 MB (3,359,673 bytes) 24
Purges RecoverableItemsPurges 0 B (0 bytes) 0
Versions RecoverableItemsVersions 0 B (0 bytes) 0
At the same time, yes, this user has 1 more box attached through "full access permission management". But there and then obviously not 1k folders.
How can I see from which computer or IP sessions are open to this mailbox?