Slamming Spam
By Andrew S. Hughes
Every month, the University of Notre Dame's e-mail servers receive millions of messages.
Not all of them receive a warm welcome.
For example, in a two-month period, the central mail servers rejected 4.1 million of 15 million messages and tagged another 1.9 million of them as suspected spam.
"The gross analysis two-month study is that approximately 25 percent of the messages presented to our mail servers are rejected, because they come from known spam sources," senior systems administrator for Messaging Services Paul Russell says. "Approximately 20 percent of those we accept are tagged as suspected spam."
The University installed a new e-mail system in March 2003, and with it came increased security against spam -- unsolicited commercial messages.
"It's not about content," Russell says. "It's about consent, and if you don't have permission to send commercial e-mail to me, it's spam."
Messaging Services oversees four servers that constitute the University's e-mail cluster. The two servers that accept incoming e-mail employ two network blacklists and a local blacklist to block all messages from known spammers.
"If a system on one of those blacklists attempts to connect to our mail servers, we reject it," Russell says. "We block a lot of spam like that. Unfortunately, we also block some legitimate e-mail. If somebody has a problem sending e-mail to Notre Dame, they can send something to postmaster@nd.edu to report the problem."
In addition to the blacklists, the application SpamAssassin analyzes all incoming e-mail for tip-offs that a message might be spam.
"It will scan a message looking for characteristics that are commonly found in spam," Russell says. "The authors of this product (SpamAssasin) have a huge body of known spam they use to identify characteristics that are likely to appear in spam, as well as characteristics that rarely appear in spam."
Individual users can use the enterprise directory services (EDS) Email Options page to enable spam filters, and create personal blacklists and whitelists.
“It's estimated,” Russell says, “that 50 percent of e-mail is spam, and that adds up to huge human and economic costs as people spend time deleting spam and filing complaints over objectionable material in spam they've opened.”
There's also a technological cost.
"We have approximately 300 gigabytes of messages in mailboxes on the mail servers," Russell says. "If you figure 25 percent of that is spam, that's 75 gigabytes, and that's just what got delivered. We have to invest more in hardware resources, and we have to spend more time and money buying, installing and fine-tuning our spam filters. We have to have probably a third to half more disk space than what we'd need if there were no spam in the world. One piece of spam doesn't cost much in time or resources, just like one little paper cut won't hurt you, but when you start adding it up, it's like death from a thousand cuts."