[exim] reject html letters and gif attachments!

good morning my dear brothers of spam fighting corps.! :D
now my problem is going panic state - flooded over with spam so making
some cardinal decisions.
and at first - plain text letters only, what will you say. is your
experience showed good results or it's not worth because of users feel
ungood ?
and filter image attachemetns the second.

i'm using exim 4.62 on gentoo with exiscan and exiscan-acl flags enabled.

how can be that possible and released ?