Originally Posted by Kevin
Most email clients can cache email locally for off-line reading of imap email. In fact I wish I could disable that feature in ThunderBird as it is a complete waste of disk space in my case. There are also local folders where you can move your email to so that it is local only if you want to.
I should have looked harder. I had almost 300MB in a "Cache" folder within my .thunderbird dir but the OfflineCache folder was empty as I had the feature properly disabled. I just looked in the configuration editor and found browser.cache.disk.enable which I set to false and now I no longer have that waste of 300MB of disk space
Note that I consider it a waste because my IMAP server is the same computer that serves the NFS where my home directory is stored. Therefore the cache was just as remote as the email. In fact they are on the same physical storage device (a software RAID1 volume).