If you have a question and you want to ask multiple people or groups, do not send the question individually to each group. Just send the question once with your recipient list on the To line.
If you send it individually, then each recipient will not know that you asked the question to other groups as well. This in turn creates wasted effort because one group won't know that another group already answered your question (or has already started researching it).
For example, one person asked the same question on a shell-related discussion group, again on a Windows 2000 discussion group, and a third time on a Windows XP discussion group. I research the problem and responded on the Windows XP discussion group. Meanwhile, one of my colleagues researched the problem and responded on the shell discussion group. (The two answers were the same.) Congratulations, you created twice as much work as necessary. To prevent it from going to a triple, I replied on the Windows 2000 group saying that the issue has been taken care of.
Just because we don't charge billable hours to your team doesn't mean that our time is free.
I see a variation of this happening in blog comments as well. Somebody will ask the exact same question to Larry Osterman, Michael Kaplan, and me. Now, first of all, I specifically do not provide technical support (it's spelled out in the Contact Page), but that doesn't stop people from trying anyway. Even if you think your question is of general interest and put it into the Suggestion Box, that doesn't mean that I'll agree with your assessment, and even if I do, given the historical rate at which I accept topics from the Suggestion Box, you won't get an answer for around three years.
One particularly insistent person not only sent the question to Larry and me, they even did it after opening a case with Microsoft developer support! (How do I know? Because developer support forwarded the question to my team.)