Symptom: Large mail.que file size
This is the file in which exchange manages its queues before finally delivering emails. It is usually located in <Exchange_Installation_Path>/TransportRoles/data/Queue
Solution: Rebuild queue files
Like the EDB mailbox databases, the queue file generates white space that can only be recovered by rebuilding it. After performing the following procedure, the extra space mail.que file is using will be recovered:
Run this powershell command to ensure there are no queued messages
[PS] C:\> Get-Queue | select-object Identity,MessageCount Identity MessageCount -------- ------------ EXCHSRV1\4 0 EXCHSRV1\5 0 EXCHSRV1\6 0 EXCHSRV1\7 0 EXCHSRV1\8 0 ...
Stop Transport service
Move Queue files
Move the contents of the “<Exchange_Installation_Path>/TransportRoles/data/Queue” folder to another path. If you are in a critical situation (out of space), you can move them to another disk.
Start Transport service
After performing some mail flowing tests (for example send and receive new emails, check the modified date of the queue files is changing…) and if everything went ok, the old files can be safely deleted. Just in case you can wait a reasonable time to do it. Sysadmins always should have a plan B. 😉