I remember something similar, one time I got spammed through whispers by several people at the same time, they were in a different district. So i made screenshots and sent it, stating explicitly that I couldn't report them because I wasn't in the same district as they were.
Quote:
They would reply me with stuff like "the incident is being investigated blablabla we cannot inform you if any action has been taken".
I got exactly that message and added to that was the instructions to use the /report function instead of sending them e-mails, and that I didn't have to bother sending an e-mail back to them. Even though I stated quite clearly that /report didn't work because they were in a different district.
When I saw that I had good enough proof (for myself, since it's not conclusive on a large scale) to know that they simply don't read what I have to say. So if they don't even read our emails, you can be pretty sure they don't mind /report information either.
Location: In my own little world, looking at yours
Guild: Only Us[NotU]
Profession: E/
When they leave the zone you are in, screen shot and email to ANet. Slower, but it does work. Zapped a couple of gold sellers that way. Took 3 minutes to report and in less than 10 minutes they were "offline".