I just downloaded Thunderbird as my mail client, but when logging in, there were these two option.
As far as i could read, PPOP (i think it's called) was more secure than IMAP, but i couldn't login with the mailbox on the computer as they said. Only online.
This is a Highly Secured Data mail client for those who wants to be untraceable and stealth. It's amazing and it works. Your ISP is unable to hook your mails with this protocol. IP-HSD contains incredible functions such as SLOTS and many more functions.
I found IP-HSD on SourceForge but you can...