Xobni Snooping on our E-mail Volume?

When clicking on the help '?' in the bottom pane of Xobni I noticed my browser opens up to a URL which includes the fields number_emails and xmid (presumably my user id) before quickly redirecting to the help page.

I'm not particularly offended or concerned but I do believe this is a minor case of personal information being volunteered without consent.

The interesting question is where should the line be drawn? Is it ok for applications to gather any personal information from users without their consent? If so, what determines acceptable vs. unacceptable information? What if it were Microsoft collecting these numbers and user id's instead of Xobni?

http://www.xobni.com/support?version=1.2.3.3644&outlook=Outlook2007&windows=Windows+Vista+(Microsoft+Windows+NT+6.0.6000.0)&number_emails=44135&xmid=6507C56D82384B66B41C337F366C5D35