MIME Types

[Deeztek Support]

According to the amavis docs, amavis checks MIME types of decoded mail 
parts where the content classifications are provided by a file(1) utility.

Which file(1) utility does amavis use? I tried using the file command as 
follows:

file -k -i file.rar

I got the following:

file.rar: application/x-rar; charset=binary

So, I inserted a file rule banning application/x-rar MIME types, I sent 
an email with an attached .rar file but the email with the attachment 
came through.

I realize that I can just use the .rar file extension to block those 
file types and that works, however, I want to use the MIME type instead.

How would I go about finding the MIME type of a file amavis recognizes 
certain files as?

Thanks a lot