The remote host has a mail client installed that is affected by a memory corruption vulnerability.
Versions of Thunderbird 10.x earlier than 10.0.1 are potentially affected by a use-after-free error in the method 'nsXBLDocumentInfo::ReadPrototypeBindings' and XBL bindings are not properly removed from a hash table in the event of failure. Clean up processes may then attempt to use this data and cause application crashes. These application crashes are potentially exploitable.
Upgrade to Thunderbird 10.0.1 or later.