The file: 'aliases.conf' should be in the config directory ($config_dir). By default, /etc/rslight

The file is similar to, but not exactly the same as a mail aliases file.

Here's an example:
admin:the_big_guy
sysop:the_big_guy
three:userthree
test this:some_user
four:userfour
five:userfive
some.user:some_user

You may have multiple lines pointing to the same user, but you may NOT:
one:userone
userone:usertwo
usertwo:userthree
two:usertwo,userthree

The username to the right of the colon must always be a real username, and only one username.

It is suggested to add 'admin' and 'sysop' to point to the administrative user. Add any others you wish.

When a user creates an alias in their Configuration, that alias will be added to this file automatically. By default, only one alias per user. (see further info below)

Aliases are mainly used for mail. So mail sent to 'admin' will end up in the mailbox of 'the_big_guy' from the example above. Right there is a good reason to always create an admin and sysop alias, so your users don't have to guess who is the admin.

overrides.inc.php contains two modifications for the use of aliases:

'reserved_names' => array("admin", "sysop", "rslight"),
Reserved names are aliases that may only be added manually to aliases.conf. A user may not use these names in their Configuration to create an alias. Add whatever you wish here (in array format).

'duplicate_aliases' => array("the_big_guy"),
Duplicate aliases are users who are allowed to have more that one alias. The admin will fall into this category. Add any other users you wish.

Have fun!

--
Retro Guy