E-mail is definitely a business critical tool, you just can't live without e-mail. However there are a lot of threats that make e-mail also a very vulnerable tool, you need to protect yourself against virusses and spam.
The best solution to protect your e-mail today is via the Ironport mail firewall. This mail firewall acts as a mail relay with optional anti-virus and anti-spam protection. Sophos is used as the anti-virus engine, for anti-spam you can choose between the built-in anti-spam engine or use the Brightmail anti-spam engine.
The unique SenderBase network is used to block spam mails as well as new virus outbreaks very accurately.