RFC 3028 

Proposed Standard 

T. Showalter, Sieve: A Mail Filtering Language, January 2001.

RFC 3431 

Proposed Standard 

W. Segmuller, Sieve Extension: Relational Tests, December 2002

RFC 3598 

Proposed Standard 

K. Murchison, Sieve Email Filtering -- Subaddress Extension, September 2003

RFC 3685 

Standards Track 

C. Daboo, Sieve Email Filtering: Spamtest and VirusTest Extensions, February 2004

RFC 3894 

Standards Track 

J. Degener, Sieve Extension: Copying Without Side Effects, October 2004