CVE-2007-5855
Mail in Apple Mac OS X 10.4.11 and 10.5.1, when an SMTP account has been set up using Account Assistant, can use plaintext authentication even when MD5 Challenge-Response authentication is available, which makes it easier for remote attackers to sniff account activity.
Date published : 2007-12-19
http://lists.apple.com/archives/security-announce/2007/Dec/msg00002.html