Linux: Email - 2

Concluding part of email discussion..

-configuring sendmail:
-config files reside in /etc/mail. Primary file is sendmail.cf.
-this file is not edited directly--the corresponding sendmail.mc file is edited.
-sendmail reads the corresponding *db files in the same dir.
-*db files are generated using 'makemap' cmd.
-the config files contain 'dnl' keyword in beginning and end of certain lines.
-dnl = delete to new line; dnl causes the daemon to ignore rest of the line. so dnl is used for comments.
-after editing sendmail.mc, restart sendmail to regenerate the sendmail.cf file and restart daemon.
    # /sbin/service    sendmail  restart
-certain other files exist in /etc/mail like:
    . mailertable    -    forwards emails from one domain to another
    . access    -    sets up a relay host
    . virtusertable    -    serves email to multiple domains, like alias
-spamassassin is a tool for preventing spam which accounts for three quarters of all email
-spam is more correctly, unsolicited commercial email.
-spamassasin does analysis of mail header, text, blacklists etc.
-spamassasin is accessed via spamc cmd.
-eg:    $ echo 'hi there' | spamc
-webmail - mail accessed over the web eg: gmail
-webmail allows you to access email from anywhere on the Internet, unlike dedicated clients like thunderbird.