Bell Sympatico uses Symantec Brightmail to scan and remove infected attachments on the server level. I have used Sympatico for 5 or 6 years and have never had a single infected attachment make it to my inbox.
I say no need to run Internet Mail provider. Any decent software firewall will warn of outgoing spam and whatnot, plus have the ability to block it.
Quoted from
http://www.symantec.com/Products/enterprise?c=prodinfo&refId=835-----------------------------------------------------------------------------------
Key Features
* Catches spam with a 95 percent effectiveness rate.
* Prevents false positives with a 99.9999 percent accuracy rate (less than 1 false positive in every million messages).
* Automatic, timely, and secure updates every 5 to 10 minutes.
* Backed by global operations centers in the United States, Ireland, Australia, and Taiwan.
Key Benefits
* Built on award-winning technology that protects over 300 million users worldwide.
* Brightmail AntiSpam solutions are used to filter over 15 percent of worldwide email and over 100 billion emails per month.
* Nine of the top 12 U.S. Internet Service Providers rely on Brightmail AntiSpam solutions to protect their subscribers.
* Backed by global operations centers in the United States, Ireland, Australia, and Taiwan.