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Various mail handling programs
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mailx (heirloom)
   The default "mail" command on redhat/fedora systems
   Capable of actually sending to SMTP servers directly with some
   configuration (WHY???)

   See "mailx.txt"  and  "mail_sending.txt"


esmtp
  User level sendmail uploader
  No daemons needed

    cp /usr/share/doc/esmtp/sample.esmtprc ~/.esmtprc
    vi ~/.esmtprc
      hostname = smtp.example.com
      qualifydomain = example.com
      force sender = {your_email_address}
      force reverse_path = {your_email_address}

  Failed to send mail is queued in "/home/user/.esmtp_queue"
  and tried again when next mail is attempted.

  WARNING: you will not have a local mail deamon to pickup mail
  So mail programs need to use the "sendmail" program, connected to this.

  Failed to get it working - little debug output - project discontinued


ssmtp   Like esmtp but with system level configuration

  Attempts to send mail immediately, but on failure it will be saved in
  a 'dot' sub-directory, and will be retried next time a mail is sent.

    # check symlinks  /etc/alternatives/mta
    #   alternatives --display mta

    # set a smarthost delivery server...
    vi /etc/ssmtp/ssmtp.conf
      mailhub=esmtp.example.com

    # set the sender address, and destination host for individual users
    vi /etc/ssmtp/revaliases
      anthony:{your_email_address}:esmtp.example.com

  Works very well, but clawmail needs to use the 'sendmail' command to send
  mail, rather than try to contact the local daemon, that way ssmtp will do
  the delivery.

  Sending mail with '-v' verbose wll let you watch the SMTP protocol
  interaction to discover where problems lie.


swaks    SMTP Server Test Mailer

    swaks --to user@example.com --server smtp.example.comu

    swaks --to user@example.com --from tester@example.com \
          --server smtp.example.com --add-header 'Subject: Testing 1 2 3'

  See also "mail_sending.txt"

dumbster  SMTP mail collector.  Just collects mail, does nothing with them

EMailRelay
  Extrememly light-weight, with a no-frills phylosophy to get in the way of
  what YOU want to do.  Mostly controled by command line but with some
  secondary files.  Remote clients are off by default but can be enabled with
  access and authentication controls.  A filter can be used to modify the mail
  or envelope during the process.

  http://emailrelay.sourceforge.net/
  https://ftp.net-snmp.org/projects/emailrelay/reviews

  A general mail relay program with 4 modes of operation...
    Server  -- receive mail into a queue
    Client  -- send stored mail to a real smtp host
    Proxy   -- pass mail on immediatally reporting failures to client
    Pop     -- allow download of stored mail

  Used for a mailproxy  server to redirect the envelope address
  of all recieved mail to a specific mailbox (for development debugging)

smtpprox
  http://bent.latency.net/smtpprox/
  A perl framework to accept a mail, then forward it on.

  The wrapper program creates a pool of servers, each of which
  service a randomised number of clients before dying.

  By itself it makes no changes -- basically a frame work program.

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