I receive all of my email to my own domain through register.com
and I use fetchmail to pop it off. I just got an email from them
saying they're going to switch to SMTP. Which doesn't make much
sense to me, isn't SMTP for sending mail?
Taken at face value, for an ISP to change from POP or IMAP to SMTP
would mean that they will no longer provide a mailbox and you will
no longer need fetchmail. Instead, they will push the mail to your
mail server (SMTP receiver) as it arrives. That's the way mail is
"really supposed to work", and should be just fine if you have an
always-on connection like DSL. It may not be so great if you have
a dialup.
Another possibility is that the notification is mixed up, and they
really intend to switch from POP to IMAP. That is also a Good Thing,
since IMAP is superior to POP in almost every respect.