MH-E can sign and encrypt messages as defined in RFC 3156. If you should choose to sign or encrypt your message, use one of the following commands to do so any time before sending your message.
The command C-c C-m C-s (mh-mml-secure-message-sign)
inserts the following tag:
<#secure method=pgpmime mode=sign>
This is used to sign your message digitally. Likewise, the command
C-c C-m C-e (mh-mml-secure-message-encrypt) inserts the
following tag:
<#secure method=pgpmime mode=encrypt>
This is used to encrypt your message. Finally, the command C-c
C-m s e (mh-mml-secure-message-signencrypt) inserts the
following tag:
<#secure method=pgpmime mode=signencrypt>
This is used to sign and encrypt your message. In each of these cases,
a proper multipart message is created for you when you send the
message. Use the command C-c C-m C-n
(mh-mml-unsecure-message) to remove these tags. Use a prefix
argument (as in C-u C-c C-m s e) to be prompted for one of the
possible security methods (see mh-mml-method-default).
The option mh-mml-method-default is used to select between a
variety of mail security mechanisms. The default is ‘PGP (MIME)’
if it is supported; otherwise, the default is ‘None’. Other
mechanisms include vanilla ‘PGP’ and ‘S/MIME’.