sendmail, 4th Edition

Add smmsp to /etc/passwd

When sendmail is run as non-set-user-id root, it is run either as root when it is invoked by the root user, or as another user when it should not run as root. The sendmail distribution clearly cannot divine ahead of time what user you wish to use when not running sendmail as root. It could have chosen nobody, for example, but the user nobody does not exist under all versions of Unix.

You can choose your own username by using the confMSPQOWN build macro (confMSPQOWN on page 91) to place a line such as this into your build m4 file:

define(`confMSPQOWN', `nullmail')

If you change the username, you will also have to build and install your own submit.cf file, and include in the mc file, for that creation, a definition for the new users with the RunAsUser option (RunAsUser on page 1083), like this:

FEATURE(`msp')
define(`confRUN_AS_USER', `nullmail')

If you don’t change the name, sendmail will use the name smmsp, which stands for SendMail Message Submission Program.

Whether your keep the username chosen by the sendmail distribution, or choose a name of your own, you will need to add that name to your system’s passwd(5) services. Here we show how to do this with the traditional Unix passwd(5) file. Consider the lessons taught here, and apply them to your passwd(5) services in the manner most suitable to your Unix system:

nullmail:*:32764:32764:Null Mail:/no/such/directory:/bin/false

In this example of a line from a traditional Unix passwd(5) file, we have elected to create ...