@Peter Xenios
Hi,
Did the mailbox get migrated recently?
If so,the result from the command Get-MailboxStatistics -server <servername> may be showing a soft deleted mailbox.
To confirm it,you can run this command:
Get-MailboxStatistics -server <ex2007servername> | fl displayname,disconnectreason
If the disconnectreason shows "softdeleted",it may be the cause.
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