The sendmail configuration file ( controls how your server sends and receives E-Mail. It uses options, rules, and other directives to modify the behavior of the sendmail program. Because of the sendmail configuration file's complexity, many have shied away from modifying the default sendmail configuration.

Creating and customizing a configuration file is much easier if you use the m4 macro preprocessor. The m4 preprocessor reads directives from a file whose name ends with .mc (for "macro configuration") and generates a sendmail configuration file in a file whose name ends with .cf. When you rename the file to and store it in your server's ~/etc directory, it becomes your sendmail configuration file.


We have created an easy program to install the sendmail configuration utilities, including m4 macros for generating sendmail configuration files on your Virtual Private Server. Simply run the following command from your Virtual Private Server SSH or Telnet prompt.

% vinstall sendmail

The installation script installs the macros and sendmail configuration tools in the directory ~/usr/local/sendmail and its subdirectories. It does not change your existing sendmail configuration file or setup in any way! The m4 macros include slight modifications for the Virtual Server environment.

Some sample .mc files (and corresponding .cf files) are installed into the directory ~/usr/local/sendmail/cf/cf. They illustrate how to control spam with the access.db and by querying the online anti-spam databases.


A sizable README file documents many additional features, and gives numerous examples. The README file is located at ~/usr/local/sendmail/cf/README.

Chapter 19 of the second edition of the book Sendmail by Bryan Costales and Eric Allman (Sebastopol, CA: O'Reilly, 1997) describes the procedure for generating configuration files with the m4 macro preprocessor.

Additional information is available online:

Please note: the information on this page applies to ITS web hosting plans. It may or may not apply to other environments. If you are looking for a feature described here, or better support from your hosting provider, please consider hosting your site with ITS!

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