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SMTP Require TLS Option

The information below is for an old version of the document.
Document Type This is an older version of an Internet-Draft whose latest revision is Replaced
Author Jim Fenton
Last updated 2016-08-16 (Latest revision 2016-02-13)
Replaced by draft-ietf-uta-smtp-require-tls, RFC 8689
Stream (None)
Expired & archived
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Expired
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


The SMTP STARTTLS option, used in negotiating transport-level encryption of SMTP connections, is not as useful from a security standpoint as it might be because of its opportunistic nature; message delivery is prioritized over security. This document describes a complementary SMTP service extension, REQUIRETLS. If the REQUIRETLS option is used when sending a message, it causes message delivery to fail if a TLS connection with the required security characteristics cannot be completed with the next hop MTA or if that MTA does not also advertise that it supports REQUIRETLS. Message originators may therefore expect transport security to be used for messages sent with this option.


Jim Fenton

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)