You can configure Sendmail to encrypt emails you want send and receive, via the secure socket layer (SSL).
To begin, open your sendmail configuration file in a text editor with write access:
# vi /etc/mail/sendmail.mc
Now append/modify following directives:
-- location to find certificates
-- Root Bundle file (Make sure you select your server software as Apache & mod_ssl)
-- Domain Certificate
And make sure port is set to smtps (secure smtp i.e. port 465):
DAEMON_OPTIONS(`Port=smtps, Name=TLSMTA, M=s")dnl
Now, restart Sendmail and secure POP3s/IMAPs
Please note the following:
- all certificates are provided in PEM andÂ PKCS #7 format.
- .key file needs to have owner read/write permission for the owner, not group.
- define(`confLOG_LEVEL', `14')dnl ## Will help with debugging. Can be commented out or put back to its default level of 9 when done.