Attachments

I have installed Exim mail server, I whould like to block the following file extentions:

chm, cmd, com, cpl, crt, eml, exe, etc

I found the file attachments.filter but don't know how to configure this file (I have attached file), so kindly if some one help me to configure this file..

I already uncomment the following line in exim configure file:

message_body_visible = 5000
message_filter = /mnt/router/packages/exim/attachments.filter

thenks