2.1 Add the group and user

Mailman requires a unique user and group name which will own its files, and under which its processes will run. Mailman's basic security is based on group ownership permissions, so it's important to get this step right1. Typically, you will add a new user and a new group, both called mailman. The mailman user must be a member of the mailman group. Mailman will be installed under the mailman user and group, with the set-group-id (setgid) bit enabled.

If these names are already in use, you can choose different user and group names, as long as you remember these when you run configure. If you choose a different unique user name, you will have to specify this with configure's --with-username option, and if you choose a different group name, you will have to specify this with configure's --with-groupname option.

On Linux systems, you can use the following commands to create these accounts. Check your system's manual pages for details:

    % groupadd mailman
    % useradd -c"GNU Mailman" -s /no/shell -d /no/home -g mailman mailman


... right1
You will be able to check and repair your permissions after installation is complete.