The remote host is missing an update as announced via advisory SSA:2006-166-01.

https://secure1.securityspace.com/smysecure/catid.html?in=SSA:2006-166-01

New sendmail packages are available for Slackware 8.1, 9.0, 9.1, 10.0, 10.1, 10.2, and -current to fix a possible denial-of-service issue. Sendmail's complete advisory may be found here: http://www.sendmail.com/security/advisories/SA-200605-01.txt.asc Sendmail has also provided an FAQ about this issue: http://www.sendmail.com/security/advisories/SA-200605-01/faq.shtml The CVE entry for this issue may be found here: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1173