If there have been fewer junk e-mails about genital enlargements and paid Caribbean vacations to delete from Yale mail inboxes lately, students probably have Information Technology Services to thank for the relief.

In response to the worldwide surge in spam in recent months — a trend propelled by the increase in “computer bots” controlled by spammers — ITS installed additional software in its e-mail spam-filtering system early last month that is dramatically curbing the influx of unwanted mail, ITS representatives announced this week.

The software, called Cloudmark Authority, has increased the number of spam e-mails ITS’ spam-filtering system detects by 103 percent, John Coleman, Yale’s e-mail-systems administrator, said. With the new plug-in, the system now catches 200,000 spam e-mails per day, up from between 50,000 to 100,000 messages, he said.

Coleman said the recent increase in spam is not a phenomenon unique to Yale, but the University was the first academic institution to purchase the Cloudmark Authority software.

Cloudmark Authority is a feedback database that catalogues various definitions of spam submitted by users from around the world. If an e-mail falls under one of these proposed definitions, it is treated as spam and blocked, Coleman said.

The Cloudmark add-on, which relies on constantly changing feedback, may eliminate the need for ITS to continuously revise the spam filtering system, he explained.

“Types and varieties of spam keep changing all the time — that’s one of the most challenging parts about it,” he said. “But because [Cloudmark Authority] relies on real-time user feedback, it self-adapts as spam diversifies.”

The database was installed to strengthen the last level of filtering of what Coleman called “a layered approach to spam reduction.” Under this system, millions of e-mails from known spam senders are blocked outright before they even enter the Yale Web mail system. If they get past this first filter, messages are scanned for viruses and finally scored on a scale for spam content, he said. E-mails scored at a three enter the “tagged-spam” folder but are not deleted, he said.

The announcement comes at a time when spam traffic is at an all-time high and rising steadily, he added, as a result of the increased ease, affordability and profitability of sending out spam, even if typical response rates are low.

Coleman said Yale relies heavily upon open-source spam services such as the Cloudmark Authority software — which more accurately identify spam that ITS alone could — to avoid “false positives,” e-mails the system falsely tags as spam.

Cloudmark Authority may indeed have proven itself effective: students interviewed said they have noticed a significant reduction in the number of unwanted e-mails in their inboxes over the past month.

“I used to get a lot of spam in my Yale mail,” Alexandra Van ’08 said. “I haven’t received many lately … and for the first time, I didn’t receive any over the holidays.”

Justin Baker ’08 said that, if the reduction in spam is due to the new program, he is pleased with how ITS has begun to handle spam.

“I certainly used to get an absolute ton of spam, but there has been a marked decrease over the last couple of months or so,” he said. “I use Outlook for my mail, and that has spam filters also, so I’m not sure where the credit goes, but it seems like ITS is at least doing a much better job than they were doing not too long ago.”

But other students — like Tam Nguyen ’11 and Jacqueline Madison ’09 — said they did not receive much spam to begin with, so they have not noticed a reduction over the past month.

Still others — like Eric Bank ’08 — bypassed the worldwide rise in spam by avoiding the Yale Web mail system altogether. He said he never checks his Yale mail and instead forwards all mail to his Gmail account, which has a strong spam filter.

While the Yale system catches the majority of incoming spam, students can take steps to further block unwanted messages, Coleman said. Students should keep their filters at the highest setting, protect their computers from viruses and avoid turning off the “spam filter” on their Yale mail settings, he said.