sendmail administration

sendmail has several key features:

• implements a general internetwork mail routing facility, featuring aliasing and forwarding, automatic routing to network gateways, and flexible configuration.

• is a mail router that collects messages generated by a Mail User Agent (MUA) such as mail(C), determines a route for delivery, edits the message header as required by the destination and delivery agent, and calls an appropriate delivery agent (called a mailer) to deliver the mail. Typical delivery mechanisms include TCP/IP (using SMTP), UUCP, x.400, and local delivery programs such as lmail.

• supports either Internet-style addressing, such as user@domain, or UUCP-style addressing, such as host!user.

• supports delivery of mail with X.400-style addressing to an X.400 gateway machine if such a machine is specified in the configuration.

• supports anti-spamming. See ``Managing spam''

• handles text format files only. Binary data is not allowed unless included in the mail message as a uuencoded file. See the uuencode(C) manual page.
  

• is based on:
  
  RFC 822 (Internet Mail Format Protocol)
  RFC 821 (Simple Mail Transport Protocol)
  RFC 1123 (Internet Host Requirements)
  RFC 1425 (SMTP Service Extensions)

  However, in many cases sendmail can be configured to exceed these protocols, as described in this chapter.

• does not provide a user interface for composing and reading mail, nor does it do actual mail delivery. These tasks are handled by the MUA and the mailer, respectively.

• is difficult to configure manually. This implementation of sendmail, however, includes a script that creates a basic configuration that is adequate for most sites. For additional information on how to manually fine-tune this configuration, see: ``Tuning sendmail configuration'' and ``Advanced sendmail configuration''

See also:

• ``How sendmail works''

• ``Standard sendmail configuration''

• ``Reconfiguring sendmail''

• ``Administering sendmail''

• ``For more about sendmail''