rapid7/metasploit-framework — pull request #3256 by TomSellers (2014-04-14 18:28:38+00:00)
Title: Update to openssl_heartbleed to deal with SMTP RFC

Added CR character in order to have the commands match SMTP RFC 5321 2.3.8 for line termination. Some SMTP services, such as the Symantec Mail Gateway, require strict compliance or the connection will be dropped with the response '550 esmtp: protocol deviation';

This has been seen during testing.

Reference:
http://www.symantec.com/business/support/index?page=content&id=TECH96829
http://tools.ietf.org/html/rfc5321#section-2.3.8