The /etc/mail/sendmail.cf file was designed to be quickly parsable by sendmail, not to be human-readable, and it's widely considered to be one of the most cryptic things a Unix administrator needs to deal with. So, starting with version 8, a set of macros for the m4 macro language were written to make it much easier to create, modify, and maintain all of the common configurations for the sendmail.cf file. The file which contains these macros is called a .mc file.
| .cf Files | .mc Files | |
|---|---|---|
| Flexible | very | not totally, but covers 99% of situations |
| Understandable | no | yes |
| Quickly machine-parsed | yes | no |
The .mc files are kept in the cf/cf directory of the sendmail source tree. This tutorial will only cover some of the more commonly useful configuration macros. For a more complete list, see the README file in the upper cf directory.
