I am running Release 8.0.3_GA_5664.RHEL6_64_20130305090204 CentOS6_64 FOSS edition and am running low on available drive space-- so I started looking for email boxes to clean out. After identifying several system emails which act as archives for us, I use the program Mailstore Home to "archive" the emails. It first synchronizes folders between its local copy and the server IMAP folders. Once the local copy is confirmed/verified, it then deletes the original from the IMAP folder on the server.
Here's the problem... although I successfully archived 140k of 180k emails in an account--which caused the folder size to drop from 13Gb to 3Gb-- the available drive space on the server did not change by much, perhaps 100Mb became available. I repeated this process with other mailboxes, but although I offloaded 25Gb of email, server drive space is almost unchanged.
What do I need to do to free the disk space? I already checked all trash cans and they are all empty.