If you have a mailbox in Exchange 2013 and Exchange 2016 that is disconnected. it will automatically be delete when it hits the limit on your mailbox retention policy, to stop it from being deleted you must attach the mailbox to a user account. This can be done with a power shell command as seen below. First though , we need to find the GUID of the mailbox we want to attach in Exchange 2013 or Exchange 2016.
Exchange 2013/2016 – Find Mailbox GUID
This is done with the power-shell below.
Get-MailboxStatistics -Database MB | fl DisplayName,MailboxGuid
Where “MB” is the name of your mailbox database, it will display like the output below. Make a note of the guide you need.
[PS] C:\Windows\system32>Get-MailboxStatistics -Database MB | fl DisplayName,MailboxGuid
DisplayName : SystemMailbox{f43bb8a4-a5c9-4ca7-881a-48fac82016f6}
MailboxGuid : 003dcac7-d369-45a0-b664-81cfbd45136b
DisplayName : Microsoft Exchange
MailboxGuid : b0f4014b-12ea-47ce-9b78-5252d41ac143
DisplayName : Microsoft Exchange
MailboxGuid : 6eb3760c-e619-43a9-83f2-5c1e66af5104
DisplayName : HealthMailbox73cbbe7bc31a4a9886b2ccb44dabe58e
MailboxGuid : c3293304-0118-4edc-aad2-7a574710107a
DisplayName : HealthMailboxc52c6cb7eae845b1b5f7e628185e0850
MailboxGuid : d4aa9152-48ba-4f26-b620-b86cea63a5c0
DisplayName : Personal Archive - HealthMailbox73cbbe7bc31a4a9886b2ccb44dabe58e
MailboxGuid : 4ff71e76-d777-4dc6-a691-ad129050075c
DisplayName : Personal Archive - HealthMailboxf43bb8a4a5c94ca7881a48fac82016f6
MailboxGuid : 5d7b7312-c425-4044-8d2a-9fb2c77ee883
DisplayName : HealthMailboxf43bb8a4a5c94ca7881a48fac82016f6
MailboxGuid : f83dafb2-8231-4d6c-bb75-e4682f38c1d5
DisplayName : Administrator
MailboxGuid : 0498ee56-dbeb-4f9a-bdfb-1fbc4716296c
DisplayName : Microsoft Exchange Migration
MailboxGuid : 8cc2c9a2-e6d3-4357-841b-0607a23aaacb
DisplayName : Allen
MailboxGuid : 449a9752-28be-40ff-b583-d13381d822de
Attach a Disconnected Mailbox in Powershell Exchange 2013/2016
Now that we have the GUID, we can attach it to a user object.
Connect-Mailbox –Identity 449a9752-28be-40ff-b583-d13381d822de –Database MB –user allen
Above we use the mailbox GUID 449a9752-28be-40ff-b583-d13381d822de in the database MB and we attach it to the allen user account.
Simply replace the code above with your relevant details and you can then connect a disconnected mailbox in Exchange 2013.