Description:

GNU Anubis is an outgoing mail processor. It goes between the MUA
(Mail User Agent) and the MTA (Mail Transport Agent), and can perform
on the fly various sorts of processing and conversion on the outgoing
mail in accord with the sender's specified rules, based on a highly
configurable regular expressions system. It operates as a proxy
server, independently from mail user agents. GNU Anubis can edit
outgoing mail headers, encrypt and/or sign mail with the GNU Privacy
Guard, build secure SMTP tunnels (Simple Mail Transport Protocol)
using the TLS/SSL encryption even if your mail user agent doesn't
support it, or tunnel a connection through a SOCKS proxy. Moreover,
GNU Anubis supports the remailers (it allows sending mail in an
anonymous way).

Remember, that to use per-user configuration files ident server has to
be running. Without it only system-wide configuration file is used.

If you want to use GNU Anubis with mutt mail client, install msg2smtp
package.