By agreeing to the EULA you are getting licencing approval from firstname.lastname@example.org (they write it the EULAs in the first place). If you don't understand it, or want clarification about one or more of the terms in the EULA, licence agreement, NDA or other legal document the best person to contact would be email@example.com who will give you an official response. Responses from firstname.lastname@example.org are official Microsoft policy, so if email@example.com says "Your company needs to purchase X licences of type Y" and Microsoft take you to court later you can whip out a copy of that email and the judge will take it into consideration.
IMO (IANAL), if you have some kind of written confirmation from someone reasonably believed to be a Microsoft employee acting in good faith that what you are doing is legal (eg: briankel above), and you are talking about software products valued under the tens of millions of dollar range you are probably pretty safe. I don't think any reasonable judge will be like "well you didn't e-mail firstname.lastname@example.org or get Steve Ballmer's direct approval". My understanding is employees are able to act in behalf of the company they work for, that their statements are statements of the company itself (unless stated otherwise). That's why some bloggers are careful to say things like "This blog contains my own opinions and doesn't represent the viewpoint of my employer."
The person needs to be acting in an official capacity as a Microsoft legal counsel. That means if Charles says "sure you need X licences of Y", that holds no weight in court because Charles is not an authorised legal counsel of Microsoft (actually if he made statements like that he could get fired, so he'd just forward your request to Microsoft's legal department).
But they can not reasonably sue a customer ...
The law != reason