Exim MTA: Blacklist entire TLDs

[NerdZone]

I have an RHEL3 box with Exim4, CS's (awesome!) Mailscanner Package (Thanks Chirpy!) with Spamassassin. What is the best way to block entire TLDs? (i.e. .ru .hk .de .nu ...) None of my clients have need for any comm with most foreign TLDs and my server stats back it up. I've been trying to train SA via MailWatch:

From Domain does not match the regular expression '.(us|uk|ca)'
From Domain matches the regular expression '[.][a-z][a-z]$'
SpamAssassin Score is less than '5'

Yes, it kinda makes me grin too...
I want to just block them at the MTA bypassing undeeded server ware'n tear. Still green, I just don't want to mess things up too much applying my learning curve to production equipment (never a good thing. )

Also, please let me know if I am violating any policies or Net etiquette. My intent is not to offend, just to offer better service to my clients.

Any time, insight and patience is appreciated.

[jandafields]

Chirpy's new CSF firewall has lots of options.

However, if I were a client and you were blocking all those domains, I would be unhappy. Lots of people do international ecommerce, etc. What if they have friends/family in other countries and try to send/receive email? It is a bad idea to block the entire world like that. Just use programs that blocks hacking, spam, etc.

[DGermancp]

I too would like to block MANY TLDs.
I have several domains and the only thing from those TLDs are spam