Basically what the other commenter said. It never works (except for a few canned responses) and only prompts you to install software on your computer. And how could the local client have no rate limits when the web client is always under unbearable load? It makes no sense.

I don't think it's harvesting dissident emails specifically (it wouldn't be much use for that; there will be many curious parties not just dissidents). It's just emails to spam.