Buffer overflow in Internet Mail Connector (IMC) for Microsoft Exchange Server 5.5 allows remote attackers to execute arbitrary code via an EHLO request from a system with a long name as obtained through a reverse DNS lookup, which triggers the overflow in IMC's hello response.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2002-0690
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2002/ms02-037
http://www.securityfocus.com/bid/5306
http://www.iss.net/security_center/static/9658.php
http://support.microsoft.com/default.aspx?scid=kb%3B%5BLN%5D%3BQ326322
http://bvlive01.iss.net/issEn/delivery/xforce/alertdetail.jsp?oid=20759