Deleted mailboxes will appear in disconnected mailbox list, but it will not reflect immediately. We have to wait for online maintenance to run and complete.

If we accidentally delete mailbox and if we wanted to reconnect it back then we may not be able to find it Disconnected Mailbox. We have run Clean-MailboxDatabase to get the deleted mailbox.

Eg.

Clean-MailboxDatabase \servername\SGName\Store
Cleaning Database of Individual Store

Get-Mailboxdatabase | Clean-MailboxDatabase
Cleans all the database in the Organization

Get-Mailboxdatabase | Where{ $_.Server –eq “<servername>”}| clean-MailboxDatabase
Cleans all the database in the specific store

Get-Mailboxdaatabase | Where{ $_.Name –eq “<DatabaseName>”}| clean-MailboxDatabase
Cleans all the Database which matches the specific name given in Databasename