Ok, so I put an ad on petfinder for my guinea pig, cause I'm thinking about selling him, and I'm getting back all these emails that are pretty questionable. Here's the thing that I don't get: every email I've gotten in response to my ad has the sender's email in the "to" AND "from" sections. Every other "normal" email has my email in the "to" and the sender's email in the "from". So, does anyone know what's going on with this?