We are using a combination of softwares.

command-line scanner
fast, multi-threaded daemon
milter interface for sendmail
database updater with support for digital signatures
virus scanner C library
on-access scanning (Linux)
detection of over 20000 viruses, worms and trojans
built-in support for RAR (2.0), Zip, Gzip, Bzip2
built-in support for Mbox, Maildir and raw mail files

The AntiVirus is a GPL anti-virus toolkit for UNIX. The main purpose of this software is the integration with mail servers (attachment scanning). The package provides a flexible and scalable multi-threaded daemon, a command line scanner, and a tool for automatic updating via Internet. The programs are based on a shared library distributed with the Clam AntiVirus package, which you can use with your own software. Most importantly, the virus database is kept up to date .

ANTISPAM:
Out spam database is updated with some of the best RBL's available. The mails are filtered on the basis of these RBL's thus ensuring a 80% removal of spam mails for customers.
We are now implementing a reporting, and customization system which would allow users to add their own blocks and monitor the mails being sent back.

Price: Rs. 2000 per domain per year ========SPECIAL PRICE RS. 999 PER YEAR PER DOMAIN