The remote host is missing an update as announced via advisory SSA:2003-300-02.
Fetchmail is a mail-retrieval and forwarding utility. Upgraded fetchmail packages are available for Slackware 8.1, 9.0, 9.1, and -current. These fix a vulnerability where a specially crafted email could crash fetchmail, preventing the user from downloading or forwarding their email. More details about this issue may be found in the Common Vulnerabilities and Exposures (CVE) database: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2003-0792