M-Box Open Standards conformance is listed below.

RFC 1123 Requirements for Internet hosts - application and support. R. Braden, October 1989
RFC 1734 POP3 Authentication command. J. Myers, December 1994
RFC 1939 Post Office Protocol - Version 3. J. Myers, M. Rose, May 1996
RFC 2033 Local Mail Transfer Protocol. J. Meyers, October 1996
RFC 2034 SMTP Service Extension for Returning Enhanced Error Codes. N. Freed, October1996
RFC 2045 Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies. N. Freed, N. Borenstein, November 1996
RFC 2046 Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types. N. Freed, N. Borenstein, November 1996
RFC 2047 Multipurpose Internet Mail Extensions (MIME) Part Three: Header Extensions for Non-ASCII Text. K. Moore, November 1996
RFC 2049 Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples. N. Freed, N. Borenstein, November 1996
RFC 2087 IMAP4 QUOTA extension. J. Myers, January 1997
RFC 2088 IMAP4 non-synchronizing literals. J. Myers, January 1997
RFC 2177 IMAP4 IDLE command, B. Leiba, June 1997
RFC 2342 IMAP4 Namespace. M. Gahrns & C. Newman, May 1998
RFC 2449 POP3 Extension Mechanism. R. Gellens, C. Newman, L. Lundblade, November 1998
RFC 2595 Using TLS with IMAP, POP3 and ACAP. C. Newman, June 1999
RFC 2920 SMTP Service Extension for Command Pipelining. N. Freed, September 2000
RFC 3462 The Multipart/Report Content Type for the Reporting of Mail System Administrative Messages. G. Vaudreuil, January 2003
RFC 3501 Internet Message Access Protocol - Version 4rev1. M. Crispen, March 2003
RFC 3516 IMAP4 Binary Content Extensio. L. Nerenberg, April 2003
RFC 3691 Internet Message Access Protocol (IMAP) UNSELECT command. A. Melnikov, February 2004
RFC 3894 Sieve Extension: Copying Without Side Effects. J. Degener, October 2004
RFC 3848 ESMTP and LMTP Transmission Types Registration. C. Newman, July 2004
RFC 4314 IMAP4 ACL extension. A. Melnikov, December 2005
RFC 4315 INTERNET MESSAGE ACCESS PROTOCOL - UIDPLUS extension. M Crispen, December 2005
RFC 4467 Internet Message Access Protocol (IMAP) - URLAUTH extension. M. Crispin, May 2006
RFC 4469 Internet Message Access Protocol (IMAP) - CATENATE extension. P. Resnick, April 2006
RFC 4550 Internet Email to Support Diverse Service Environments (Lemonade) Profile. S. Meas, A. Melnikov, June 2006
RFC 4551 IMAP Extenstion for Conditional STORE Operation of Quick Flag Changes Resyncronization. A. Melnikov, S.Hole, June 2006
RFC 4731 IMAP4 extension to SEARCH command for controlling what kind of information is returned, A. Melnikov, D. Cridland, November 2006
RFC 4959 The IMAP Extension for SASL Initial Client Response. Robert Siemborski, A. Gulbrandsen Sept 2007
RFC 4978 The IMAP COMPRESS Extension. Arnt Gulbandsen, August 2007
RFC 5032 WITHIN Search extensions to the IMAP Protocol. Eric Burger, September 2007
RFC 5092 IMAP URL Scheme. A. Melnikov, C Newman, November 2007
RFC 5161 The IMAP ENABLE Extension. A. Melnikov, A. Gulbrandsen, March 2008
RFC 5162 IMAP4 Extensions for Quick Mailbox Resynchronization. A. Melnikov, D. Cridland, C. Wilson, March 2008
RFC 5228 Sieve: A Mail Filtering Language. T. Showalter, January 2008
RFC 5230 Sieve Email Filtering: Vacation Extension. T. Showalter, N. Freed, January 2008
RFC 5231 Sieve Email Filtering: Relational Extension. W. Segmuller, B. Leiba January 2008
RFC 5233 Sieve Email Filtering: Subaddress Extension. K. Murchison, January 2008
RFC 5256 Internet Message Access Protocol - SORT and THREAD Extensions. M. Crispin, K. Murchison, June 2008
RFC 5267 Contexts for IMAP4, D. Cridland, C. King, July 2008
RFC 5258 IMAP4 LIST Command extensions. B. Leiba, A. Melnikov, June 2008
RFC 5260 Sieve Email Filtering: Date and Index Extensions. N. Freed, July 2008
RFC 5804 A Protocol for Remotely Managing Sieve Scripts. T. Martin, A. Melnikov, July 2010
RFC 6152 SMTP Service Extension for 8-bit MIME transport. J. Klensin, N. Freed, M. Rose, E. Stefferud, D. Crocker, March 2011
RFC 6154 IMAP LIST Extension for Special-Use Mailboxes. B. Leiba, J. Nicolson, March 2011
RFC 6851 Internet Message Access Protocol (IMAP) - MOVE Extension. A. Gulbrandsen, N. Freed, Ed. Oracle, January 2013
Draft The IMAP SEARCH=INTHREAD and THREAD=REFS Extensions. Arnt Gulbrandsen, July 2010