Political campaigns are using increasingly sophisticated methods to target messages to voters, methods that are not at all transparent. We need your help to uncover and understand them.

Back in March, we noticed that the Obama campaign was sending out many variations of the same email to voters. We asked our readers to forward their version of that message to us, to see if it this would help us understand the sophisticated ways in which campaigns target voters.

Around 200 people forwarded us that email, and what we found was that the campaign had actually sent out six distinct variations of that single message, with some interesting demographic targeting. We called our interactive the Message Machine.

But campaigns are using what they know about us to target messages in more sophisticated ways than ever — and it will take far more than one night’s analysis to understand it — so we’re expanding the experiment way past our test run.

Today, we are relaunching the Message Machine, and expanding it from handling just one mailing to handling every email from all of the campaigns in the 2012 election. It will seek a broad understanding in real time of the new and sophisticated ways modern campaigns are targeting voters.

It’s a big puzzle, and to solve it, we need a big sample of political emails, and an understanding of who received them. That’s where you come in.

If you get campaign emails on any subject — donation, get-out-the-vote, volunteering, events, etc. — just forward them to emails@messagemachine.propublica.org using your email program’s standard forwarding feature. Nothing fancier than that needed.

After a little while, once we gather enough emails to feel confident that our machine is working right, we will launch an interactive feature that will show you exactly how the campaigns are using your personal information to deliver each message.

Once you forward your first campaign mailing onto us, we’ll send you an email back with instructions on how to sign up if you want to see exactly how that message might have been targetting you.

The privacy details are easy to explain: We’re going to ask you for personal information so we can understand how the messages relate to your demographic details, but those details won’t ever appear in public in a way that can be traced back to you, and we won’t use that information for anything other than the Message Machine. We won’t share it with anybody, either. If you sign up, we'll provide you with a profile page and store your data securely on our servers.

The more emails we get, the more confident we’ll be in our analysis. We’re going to work hard to analyze the material, but the real data gathering will be done by all of you.