email filter documentation, where is it?

I , non root user, am having a ton of trouble and confusion with various email filter and boxtrapper options.

1) Is there documentation that discusses exim filters?

2) is there documentation for boxtrapper

3) I understand that exim filter file is located in /etc/vfilters/domain
however any change I make to that file is lost in subsequent attempt to update rules from cPanel. Specifing regular expression seems very difficult.

4) I have non-multually exclusive rules,
i.e.

to: begins with T send to mail.t
and
from: matches jp\\$ send to mail.jp

a message that is to:Tony... and from xxx@ddd.jp goes to BOTH mail.t and mail.jp

Thanks
Dennis German