[Dovecot] Domain blacklisting

Hello,

I run dovecot-2/Maildir/LDAP user/passdb and would like to be able to deny acess to users who connect from certain domains/IP (google.com for instance since in that case they gave their credentials to a third party).

My understanding is that I cannot use some negative form of "allow_nets". The only mechanism I can think of is tcp_wrappers. However, dovecot documentation mention it only in the dovecot-1 section. Does it work the same way with dovecot-2 ? Is it a bad idea (I'm thinking of the induced overhead) ? Can you see another way to blacklist (at dovecot application level) some sources ?

Thanks

-- Thomas Hummel | Institut Pasteur hummel@pasteur.fr | Pôle informatique - systèmes et réseau