I'm looking for an email host (ideally one who will allow me to use my own domain) that will give me shell (ssh) access to my mail. A lot of webhosts provide shell access, but only to the file storage for web stuff and not to the mailboxes/mailspool/MTA.
I can be wrong here, but maybe you can try a free shell service and set up a mail client on it.
I am a big fan of Devious, I am pretty sure you can do that with them.
If you're after a UK-based solution get in touch with me, I might be able to help you. :-)