A proposed standard filtering technology originally developed to help end users organize messages in overstuffed in-boxes instead is gaining favor as a niche tool to help in the effort to stem the onslaught of spam.
Sieve, which became a proposed Internet Engineering Task Force Standard in January 2001, is a scripting language designed to let end users write e-mail filters, such as automatically sorting incoming mail into folders based on a sender's address.
Since the Sieve proposal however, the complexity of scripting and lack of support in standard clients has conspired to keep adoption low.
But dramatic changes in the messaging landscape, most notably spam, now appear to be casting Sieve in a new light.
With the spam explosion, companies have taken mail-filtering chores from the desktop to the IT level and deployed gateways or firewalls in an attempt to stem the blitz. For vendors, such as Vircom, Brightmail, ActiveState and Rockliffe, Sieve has become a tool that lets customers write customized filters for their spam engines and even share scripts.
It could be a new life for Sieve because end-user adoption also has been stymied by the fact that in-box filtering is mostly a power-user endeavor. Also, Microsoft Outlook, which has its own filtering technology and does not support Sieve, is now the default client for Microsoft's Exchange Server and IBM/Lotus Domino, which together account for more than 200 million e-mail seats. In addition, neither messaging server supports Sieve, which can be implemented on a server or a client.
Sieve, which at its heart is a scripting language, has never had an easy-to-use GUI for end users with little knowledge of high technology.
"E-mail overload has not been the result of receiving too much legitimate e-mail. It has been because of spam," says Tim Showalter, the author of Sieve and a member of the technical staff at Mirapoint. "So filtering is now happening at the corporate gateway and not the desktop for spam, anti-virus and content. That is more interesting to customers now." Showalter's own employer, Mirapoint, does not incorporate Sieve into its products.
Regardless, Showalter says Sieve is a success and a useable specification in its current form. Showalter still is working actively on extensions, including one that will let users set up out-of-office auto-replies when away on vacation.
He also says Sieve remains a good partner for e-mail servers based on Internet Message Access Protocol, which store messages on the server where Sieve scripts can be executed for users who access mail from multiple clients.
Showalter says Sieve wasn't designed to solve the deluge of spam, which was only a trickle when he wrote the standard in the late-1990s. But some vendors have modified Sieve for use with their anti-spam engines to the surprise of Showalter.
Secure messaging vendor Vircom has enhanced the Sieve language and made it the foundation of its ModusSieve anti-spam engine, which it markets to ISPs and some corporations. Over the past year, the company says it has developed 13,000 lines of Sieve scripts, which are updated around the clock and augmented by scripts from Vircom customers who have formed the Vircom Anti-Spam Coalition.
"We are using Sieve in an unconventional manner," says Daniel Roy, product manager for ModusSieve. "We use it to work at the gateway level before messages reach the mail server." Roy says what is important is the sharing of scripts. "Sieve is an adaptive tool. We can quickly modify scripts to react to spammers and share those scripts throughout the coalition."
Sieve also is supported in products such as Brightmail's Anti-Spam engine.
"Our goal with Sieve is to give customers the ability to write custom scripts for our platform," says Ken Schneider, CTO of Brightmail. But Schneider says Sieve is not a fundamental part of Brightmail's anti-spam engine. Instead, it solves more site- or platform-specific issues, such as blocking certain attachments.
Rockliffe, which has implemented Sieve in the Web-mail interface of its MailSite Express messaging server, will use Sieve in anti-spam filtering that it plans to release in August. The product incorporates a policy editor from ActiveState's PureMessage anti-spam software. The Sieve-based policy editor has a GUI interface to mask the complexity of Sieve scripting.
"We think Sieve will be great for creating controls so users don't have to deal with junk," says Andrew Lochart, vice president of marketing for Rockliffe.
While Vircom, Brightmail, ActiveState and Rockliffe have applied Sieve to spam tools, they aren't the only ones to adopt the standard. A handful of products support Sieve, including Sun One Messaging Server, Critical Path's Messaging Server, Sendmail's Advanced Message Server and Cyrusoft International's Mulberry Internet mail client.
Users see the benefits and the limitations.
"Sieve is effective for where we are right now with 400 users," says Terry Lockwood, manager of IT for J&J Industries, a carpet manufacturer in Dalton, Ga. Lockwood and his IT staff have been writing Sieve scripts for their Rockliffe mail server for more than a year to block spam and viruses. "If we had 6,000 users we may look for another way to filter spam and viruses, but now the decision is based on economics."
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