Anyway, my isp is recommending that I switch from POP3 to IMAP. Not sure of the difference but see no reason not to go along with that suggestion and plan on doing so next week.
IMAP has a major advantage if you use more than one machine. Mail remains on the server, and can be accessed from multiple machines. It does mean that you need to trust the people running the server to keep good, current backups of your mail.
There are a few things to watch. Seamonkey (and Thunderbird) have the ability to keep mail locally. I found that it was defaulted to on when I changed to IMPAP, which meant that not only did the server have copies of my mail, I had something in the region of 440 MB of mail held locally as well. Good if you want to be able to access mail offline, but a pain otherwise.
Its fairly unusual for an ISP to offer IMAP, but you can get free IMAP from Gmail. When I changed ISPs recently (after a house move). my new ISP does not offer email at all, so I've now moved all my mail to my Gmail account. Working pretty well, especially given the amount of free space that Gmail provides. Gmail aslo provides another advantage - it is independent of the ISP, so you don't have to go through the pain of notifying all your contaces, changing mailing list addresses and so on if you do have to change ISPs.