One user tried to run an attachment in a newly received email  . After this his mailbox became inaccessible. When he tried to access it using OWA the familiar message appeared : Something went wrong.

My first thought was that the database was dismounted, but other mailboxes on the same database still worked. What’s next?

Turned out Exchange server had quarantined his mailbox. According to  TechNet his mailbox will be quarantined for 24 hours.

To list quarantined mailboxes run this PowerShell:

get-mailbox|Get-MailboxStatistics| Where-Object {$_.isquarantined -eq “True”} | ft displayname,isquarantined

DisplayName          IsQuarantined
———–                    ————-
Demo User              True

To enable the mailbox :

disable-mailboxquarantine “Demo User”