Uncheck "Automatically parse URLs", and make the link yourself with HTML <a href> tags.

<a href="http://securityresponse.symantec.com/avcenter/venc/data/w32.beagle.a@mm.html">http://securityresponse.symantec.com/avcenter/venc/data/w32.beagle.a@mm.html</a>