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Relief may be in sight for corporate users who are struggling to manage overflowing e-mail in-boxes. A promising filtering technology called Sieve is gathering support among messaging software vendors, including Sun Microsystems, Rockliffe, Critical Path, and Sendmail.

Developed by the Internet Engineering Task Force, Sieve offers a simple, universal way for users to create filters for sorting, deleting, and forwarding e-mail messages before they enter an in-box.

"Our corporate customers want the capability of an intelligent in-box," says Jeff Morris, a product line manager at Sendmail, which plans to offer Sieve filtering this fall. "They want the system to know that mail is coming from a family member and file it into a family folder. They want mail generated inside the corporation to go into a corporate folder."

Morris says Sieve helps end users who have different means of accessing e-mail--for example, Microsoft Outlook at the office and Web-based e-mail from home--create a single, unified view of their in-boxes and extend that to PDAs.

"Sieve is a way of accomplishing that by binding all the filters," Morris says.

More Messages

No one who spends much time on the Internet doubts the need for e-mail filtering techniques such as Sieve.

"The average corporate e-mail user gets about 34 messages per day," says David Ferris, president of Ferris Research, which monitors the messaging market. "It's growing at about 30 percent annually."

Most companies filter inbound e-mail for viruses, but it's not as common for companies to filter employee e-mail for spam or for questionable content. Although popular corporate e-mail packages support the creation of productivity-oriented filters such as Sieve, few users know how to take advantage of these features.

Existing tools for managing e-mail volume go largely unused, Ferris says, adding that these tools are often too tricky for end users to master.

Keeping It Simple

Sieve promises to change that dynamic by letting end users write simple mail filters based on e-mail header information using a graphical user interface. These filters are executed when messages are moved to the end user's mailbox. End users can write filters to prioritize e-mail from certain people, automatically delete e-mail from others, and create separate folders for messages from mailing lists, family members or co-workers. Filters also can be written to forward specific types of messages to the end user's handheld device.

Before the development of Sieve, messaging products from Microsoft, IBM, and Mirapoint offered e-mail filtering using proprietary techniques. As an open Internet standard, Sieve provides a common way to create and share e-mail filters across diverse e-mail systems.

Sieve is designed to run on any mail server or operating system, and it supports both the POP and Internet Message Access Protocol e-mail standards.

With Sieve, filtering is done at the server rather than the client, which means end users don't have to download messages they want filtered. This is especially useful for mobile or remote workers and those using handheld devices.

"Server-side is the way to go with e-mail filtering, especially if you don't read your e-mail in one place," says Tim Showalter, author of the IETF's Sieve document and a member of the technical staff at Mirapoint, an e-mail appliance manufacturer that has yet to announce a Sieve-compliant offering.

Ongoing Project

The IETF published Sieve as a proposed standard in January 2001, but development work continues to create extensions for vacation autoresponse messages, notifications to pagers and cell phones, and regular expressions in the Sieve language.

One challenge for Sieve is that it doesn't yet have the support of the most popular corporate e-mail packages: Microsoft Outlook and Lotus Notes.

However, larger ISPs such as AT&T use Sieve in their backbone message filtering. And a few Sieve-compliant products are available including Sun's One Messaging Server, Rockliffe's MailSite Internet messaging software, Critical Path's Messaging Server, and Cyrusoft International's Mulberry Internet mail client.

Meanwhile, Sendmail officials say Sieve-based filtering will be available in Version 2.0 of Sendmail's Advanced Message Server, due out this fall.

Behind the Scenes

Although Sieve has great potential for end users, the technology is primarily used today by network managers to filter lengthy e-mail attachments, executables and spam. This is because only a few e-mail packages--including Sun's and Cyrusoft's--support writing Sieve filters at the client.

J&J Industries, a Dalton, Georgia-based carpet manufacturer, uses Sieve filters on its Rockliffe MailSite server as an extra line of defense against viruses. Terry Lockwood, manager of IT, set up a Sieve filter to block executable attachments that aren't caught by the company's Norton Anti-Virus software.

"When the Klez virus first came out, we were getting about 40 of those a day, and they were all blocked with the Sieve filter," Lockwood says. "When the Kournikova virus came out, we had just implemented Sieve filters three weeks before that. We must have had 200 to 300 catches of that on the first day."

He says setting up the Sieve filters was "extremely easy" because of MailSite's wizardlike menus.

Next, Lockwood plans to write Sieve filters to minimize the amount of spam the company receives by using publicly available blacklists.

"Our business is increasingly relying on e-mail for correspondence," Lockwood says. "One of our competitors in town had to shut down its e-mail server for two days because of viruses, and we didn't have to do that because of our e-mail filters."

Blocking Attachments

Similarly, Thales, a Herndon, Virginia, maker of recording equipment for 911 and call centers, uses Sieve filters on Rockliffe's MailSite server to block executable attachments.

"With the Sieve filters in conjunction with our virus protection from McAfee, we haven't had a virus outbreak in over a year," says Gary Mitchelson, IT manager at Thales. "We're catching about a dozen per day."

Mitchelson wrote several other Sieve filters to block spam messages with undisclosed recipients and to serve as a backup to the company's help desk system by capturing all the trouble tickets sent via e-mail. He also uses Sieve to monitor the e-mail of employees that managers suspect are abusing e-mail or sending out confidential information.

"The Sieve filters capture everything that I've intended for them to capture, and it doesn't look like they put any load on the server," Mitchelson adds.

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