Can I have different 'senders' for each campaign?

Yes.  When you set up a campaign and then again when the campaign is sent out, you are asked to provide the sender information and the ‘reply-to’ information.  Pinpointe will then send the email out with the From and Reply-To headers set to your preference.

Here’s an excellent use for this feature.  Assume you have a regional sales team in say, New York City and your sales team will be attending (or running) a local event or trade show.  Use the ‘send on behalf of’ feature to send personalized email invitations from your regional representative to the prospects in his/her territory or region.  You can set up the entire process for the regional team and prospects can even reply directly to the salesperson.