V6 sendmail removed the concept of trusted users (Section 10.8). V8.7 reintroduced trusted users, but in a form different from that used by V5 sendmail. Now, trusted users are those who can rebuild the aliases database, and who can run sendmail with the -f switch (-f) without generating an authentication warning (X-Authentication-Warning:):

X-Authentication-Warning: host:  user  set senderto  other  using -f

To prevent this warning, the user should be added to a list of trusted users. Simply use this use_ct_file feature and add user to the file /etc/mail/trusted-users (V8.10 and above) or /etc/mail/sendmail.ct (V8.9 and earlier). You declare the use_ct_file feature like this:

FEATURE(`use_ct_file')

If you want to locate the /etc/mail/trusted-users in a different place or give it a different name, you can do so with this declaration:

define(`confCT_FILE', `/etc/mail/trusted.list')

Note that the file must exist before sendmail is started, or it will complain:

fileclass: cannot open /etc/mail/trusted.list: No such file or directory

If you want the file to optionally exist, you can add a -o (Section 22.1.2) to the conf-CT_FILE definition:

define(`confCT_FILE', `-o /etc/mail/trusted_users')

Here we retain the file's default name and location, but add the -o to make the file's presence optional.

You can also add trusted users directly in your mc configuration file like this:

define(`confTRUSTED_USERS',`root bob')

Here, two users are added to the list of trusted users, root and bob.

See also Section 10.8.1.1 for a discussion of trusted users in general.