blocking top-level-domains?

[Libor]

Hello.

we receive lot of spam mails from top level domain .ru
i am using a blacklist but the domains are always different.

i think about blocking all email with .ru ending - the whole top-level-domain

has someone already tried to block a top-level-domain?
is this a good idea or didn`t i consider anything?

how to configure postfix to make postfix blocking all .ru domains?

Thanks

Libor

[topdog]

http://www.postfix.org/regexp_table.5.html
http://www.postfix.org/access.5.html