The remote host is missing an update to sendmail announced via advisory DSA 554-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20554-1

Hugo Espuny discovered a problem in sendmail, a commonly used program to deliver electronic mail. When installing sasl-bin to use sasl in connection with sendmail, the sendmail configuration script use fixed user/pass information to initialise the sasl database. Any spammer with Debian systems knowledge could utilise such a sendmail installation to relay spam. For the stable distribution (woody) this problem has been fixed in version 8.12.3-7.1. For the unstable distribution (sid) this problem has been fixed in version 8.13.1-13. We recommend that you upgrade your sendmail package.