There's a growing convergence between scanning for email malware, and scanning for web and instant messaging malware. Eg, you need to scan both for virus-infected file transfers, spyware downloads, and traffic that has inappropriate content.
Clearly, a lot of the technology that applies to the one channel, should apply to the other channel. And you'd like to have a common administration and control tools.
Not so simple. One very big difference is that while a five second scanning delay doesn't matter for email, it matters a whole lot for web and instant messaging scanning. Web and IM scanning, and policy control, has to be done extremely quickly.
... David Ferris, with thanks to ScanSafe's Roy Tuvey