Have you ever sent a mail and asked that recipients use Reply All, only to have some people respond just to you? Then YOU have to forward the mail to the rest of the group. Thankfully, there is a way to force Outlook to send replies to a specific list of recipients regardless of whether they click Reply or Reply All.
First, when composing your message, go to the Options tab in Outlook 2010 and click Direct Replies To:
This opens the Properties dialog box. Click the Have replies sent to box and then use Select Names to add the other people on the thread (your name should be preselected; make sure you keep it!):
Once you're done adding names, click OK and then Close. Now finish your message and send it.
This actually just overrides the recipient list for the Reply button (just you by default), so that either Reply All or Reply will send to the same list if you configure it that way. Alas, it does not restrict use of the Reply All button - so if you want people to reply just to you, you'll have to hope they read closely and choose the correct button.
Or you could use Information Rights Management or even a custom email message form, but those are topics for another day.