[Exim] Suggestions on Anti-Virus for Solaris Sparc

Found out today that they would like to have Virus checking at the outside
mail server.... Currently, we have it in our exchange servers which are two
steps inside the network.

We are in the process of switching from Sendmail Switch to Exim 4.2x on both
our outside mail server and inside mail hub.

Box will be Solaris 8 (or upgraded to 9) Sun 220 with 2gb ram. Only other
function on the box will be a caching nameserver that is not authoritive for
any domains. Whole box is firewalled with only necessary ports open to the
outside.

Any suggestions on what packages are available that can be interfaced with
Exim with out a lot of fuss. Cost is somewhat of an issue but I told them
it might be $$$ and they said okay...

It is possible that this function might be moved to the mail hub between the
outside mailserver and the rest of the network but the box configuration is
the same without the caching nameserver.