AV Engine Licence

[Volkan Evrin]

I installed MailScanner and perfectly be satisfied. I install trial version
of Sophos AV Unix (not SAVI) and it is still working very well.

I want to use Sophos and Kaspersky AV engine to search the e-mails, but
local reseller said you should use SAVI licence model for each mailbox
individually.  Is it true? I have 300 clients and should I registered all
the boxes? (too much money!...)

Or, could you suggest any other free/cheap virus detection licence model or
solution that can be used with MailScanner?

Volkan Evrin