Linux Security Cookbook

8.8. Encrypted Mail with MH

Problem

You want to send and receive encrypted email conveniently with the MH mail handler.

Solution

To view an encrypted message:

show | gpg --decrypt | less

To encrypt and send a message, use the encryption features of your text editor, such as emacs [Recipe 8.1] or vim [Recipe 8.2]. Care must be taken so that only the message body, not the header, gets encrypted.

Discussion

MH (or more likely found on Linux, nmh ) differs from most mailers in that each mail-handling command is invoked from the shell prompt and reads/writes standard input/output. Therefore, to decrypt a message normally displayed by the show command, pipe show through gpg, then optionally through a pager such as less.

See Also

Further instructions for integrating MH and GnuPG (and PGP) are at http://www.tac.nyc.ny.us/mail/mh and http://www.faqs.org/faqs/mail/mh-faq/part1/section-68.html.

SSL for Securing Mail

Most major mail clients (pine, mutt, etc.) support secure POP and IMAP using the Secure Sockets Layer (SSL) protocol (also known by its later, IETF-standards name, Transport Layer Security or TLS). Most commercial mail servers and ISPs, however, do not support SSL, which is highly annoying. But if you’re lucky enough to find a mail server that does support it, or if you run your own server [Recipe 8.9], here’s a brief introduction to how it works.

A mail server may support SSL in two ways, to protect your session against eavesdroppers:

STARTTLS

The mail server listens on the normal ...