MH-E is the Emacs interface to the MH mail system. It offers all the functionality of MH, the visual orientation and simplicity of use of a GUI, and full integration with Emacs and XEmacs, including thorough configuration and online help.
Since I run this project, you'd be concerned if I gave it a thumbs-down review! :-)
MH-E is a super way to run the MH system -- it does not disturb command line usage, and it is totally integrated with Emacs as well