I used mutt for awhile but ultimately switched away from it because of two issues that came up a lot: * calendar invitations (google or outlook calendar). I could not find any program that could process the invitation, respond and save to my calendar, so I had to handle calendar invitations on my phone. I looked into writing something myself (the CALDAV protocol is plain text and not overly complicated) but never got around to it. * HTML emails -as others have noted, w3m is pretty good at rendering most emails but not all. The ones that it didn't render to plaintext well were annoying and required opening a browser to view them.

Outside of those issues, it worked great with davmail grabbing email from an exchange server, and offlineimap saving mail locally.