RFC 5231 · PROPOSED STANDARD · 2008

Sieve Email Filtering: Relational Extension

Overview

RFC 5231, “Sieve Email Filtering: Relational Extension”, is a Proposed Standard document published in January 2008 by W. Segmuller, B. Leiba. It obsoletes RFC 3431. The canonical text is published by the RFC Editor.

Abstract

This document describes the RELATIONAL extension to the Sieve mail filtering language defined in RFC 3028. This extension extends existing conditional tests in Sieve to allow relational operators. In addition to testing their content, it also allows for testing of the number of entities in header and envelope fields.

This document obsoletes RFC 3431. [STANDARDS-TRACK]

Abstract as published in the RFC, via rfc-editor.org.

What “Proposed Standard” means

An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.

Read this RFC

The canonical text of RFC 5231 is hosted at rfc-editor.org. Available in TXT,HTML.

Relationships to other RFCs
This RFC obsoletes
RFC 3431
Other RFCs from 2008

Who Is Online

In total there are 424 users online: 0 registered, 418 guests and 6 bots.

Most users ever online was 1,226 on 13 Jun 2026, 3:56 am.

Bots: AhrefsBot Applebot Bingbot Facebook Other Bot SemrushBot

Users active in the past 15 minutes. Total registered members: 354