Filtering email with Sieve

Mail Sorter

Article from ADMIN 05/2011

By Florian Effenberger

Sieve is an easy-to-use, server-based solution that can help admins intelligently filter a flood of email.

The sheer volume of email traffic today causes problems for administrators and users alike. It's not just private messages that end up in your mailbox, but also business correspondence, and even notifications from authorities. Mailing lists and newsletters also do their best to fill your inbox with all kinds of mail. To avoid drowning in this flood of mail, you need an intelligent filtering system that automatically sorts your mail into the right folders.

Users will normally set up these filters directly in the email client because both desktop applications (for example, Mozilla Thunderbird, and KMail) and web mailers (Roundcube and SquirrelMail, to name two) offer fairly comprehensive filtering options. This approach is also the simplest – as long as you only retrieve your email on a single system.

But, if you use multiple devices, things can start to get difficult. Although IMAP keeps your mail repositories identical, the protocol doesn't support filtering rules. You could theoretically copy the settings back and forth between your clients, but that is somewhat time-consuming. And, as soon as you start to use smart phones and tablet PCs, things really start to get tricky.

More Convenience with Sieve

If you manage an IMAP server and want to do your users a favor, consider offering them a Sieve filter. This tool lets them define filter rules of incoming messages, just like with Procmail, for example. The biggest advantage here is that filtering occurs directly on the server and thus happens automatically for all of the clients independently of the operating system. The rules will be applied in exactly the same way on the Thunderbird desktop, your Android cell, and your tablet PC. Sieve is the quintessential "IMAP-style" approach to filtering mail.

From the administrator's point of view, it is a good thing that Sieve integrates directly as a plugin with the Mail

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