Sieve Email Filtering: Ihave Extension
Ned Freed · 2009
This document describes the ihave extension to the Sieve email filtering language. The ihave extension provides a means to write scripts that can take advantage of optional Sieve features but can still run when those optional features are not available. The extension also defines a new error control command intended to be used to report situations where no combination of available extensions satisfies the needs of the script.