Haskell RSS, mail and XML library choices
Just to answer this question, the feed package is good for producing rss. For email, folks typically just shell out to the sendmail executable directly. The mime-mail package provides a wrapper around this along with some additional tools. If you want to read email, the typical way is to set up procmail or the like, and then use an mbox parser to interact with the generated files directly. Two parsers are mbox and codec-mbox.
If you really want to interact with pop3/imap, you can do the former with pop3-client and the latter with HaskellNet, which is pretty old but apparently works. Example code for using it is available here.