Do not delete the client when delete mail from server in IMAP protocol
I know how IMAP works, but other mail clients support the save these mail when the server to delete the message in IMAP (like foxmail). My work email space are only 4GB, so I had to deleted them from server but I hope can read/save it in client.
Alla svar (2)
On your 'home' machine or wherever it is you are accessing when not at work make liberal use of the 'local folders' feature and 'offline' feature.
Instead of just deleting messages you can move them to your Local Folders account.