[malandrew]

I reckon the admins of mail servers that are likely to be NSA targets (government mail servers or newspaper mailservers for example) could set up some sort of script that sends emails from American services (gmail, yahoo, etc) to many addresses on their own mailservers and then use another script on their mailservers to "clean up" those messages before it gets to the recipients. This would ensure that the messages get intercepted by the NSA, but never get to their intended recipient. If any link is followed, then they can be certain that the message was intercepted.

Generating messages could be done using Markov chains that learn from the content across many of their own mailboxes. Before that Markov generator is used, it could be scrubbed of any words that are particularly sensitive because they refer to classified or secret material.

That's just one idea. Now that the cat's out of the bag, I hope security researchers are already working on such honeypots. Personally, I think every major newspaper should be among the first to implement honeypots. Alternatively, people who thinks they are at risk for surveillance or suspect that they are already being surveilled should be able to submit their email to some watchdog group that can set up the honeypot on their behalf.