I am trying to send a test to 4 people, using 1and1, my ISP. Everything seems to be ok, however the emails dont get sent. The repot doesn't seem to have any errors and it says that all were sent.
Because your server deleted them. I read that article yesterday about Cox http://www.techdirt.com/articles/20060831/111504.shtml. I know you don't use Cox but your server is very likely doing the same. Nowadays internet companies and especially internet providers and web hosting companies are ran by clueless monkeys.