The remote host is missing an update to icedove announced via advisory DSA 2273-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202273-1

Several vulnerabilities have been discovered in Icedove, an unbranded version of the Thunderbird mail/news client. CVE-2011-0083 / CVE-2011-2363 regenrecht discovered two use-after-frees in SVG processing, which could lead to the execution of arbitrary code. CVE-2011-0085 regenrecht discovered a use-after-free in XUL processing, which could lead to the execution of arbitrary code. CVE-2011-2362 David Chan discovered that cookies were insufficiently isolated. CVE-2011-2371 Chris Rohlf and Yan Ivnitskiy discovered an integer overflow in the Javascript engine, which could lead to the execution of arbitrary code. CVE-2011-2373 Martin Barbella discovered a use-after-free in XUL processing, which could lead to the execution of arbitrary code. CVE-2011-2374 Bob Clary, Kevin Brosnan, Nils, Gary Kwong, Jesse Ruderman and Christian Biesinger discovered memory corruption bugs, which may lead to the execution of arbitrary code. CVE-2011-2376 Luke Wagner and Gary Kwong discovered memory corruption bugs, which may lead to the execution of arbitrary code. As indicated in the Lenny (oldstable) release notes, security support for the Icedove packages in the oldstable needed to be stopped before the end of the regular Lenny security maintenance life cycle. You are strongly encouraged to upgrade to stable or switch to a different mail client. For the stable distribution (squeeze), this problem has been fixed in version 3.0.11-1+squeeze3. For the unstable distribution (sid), this problem has been fixed in version 3.1.11-1. We recommend that you upgrade your icedove packages.