As most of you are doubtless sick of hearing by now, I’ve settled very happily on mu/mu4e to handle my email from within Emacs. It’s not the only possibility, of course, and many other Emacers prefer using notmuch, which is similar to mu but with a robust tagging system.
For those of you in the notmuch camp, KKatsuyuki has an excellent post on how to configure notmuch and offlineimap for use with Emacs. He’s got a complete recipe so you should be able to pretty much paste his configuration into your init.el making only the obvious changes to things like paths and email account info. KKatsuyuki’s configuration is for Gmail, so you may have to do a bit of research on offlineimap if you’re using something else.
KKatsuyuki’s post is an excellent go-by for anyone wanting to bring email into Emacs using notmuch.