I ran this code: http://i.imgur.com/zd5xkmD.png And according to Sendgrid, I sent over 200.000 emails - where some of my clients got over 500 emails from me. I've checked my code 100 times, and it looks completely fine to me. I believe this is a error on sendgrid's side, rather than mine. Basically I load the emails from a database. Verify if they are OK. Then send them an email. I limited the database to max 1000, so it's quiet weird how it could send 200.000 emails (over 500 to each person). Any ideas? It went through around 950 times. Far from 200.000 - the request was done within a minute. There is no way my server could push out 200.000 SMTP Requests in less than a minute!