Some aclarations about e-newsletter

Hi i need some answers about e-newsletter plugins, so little options on it, or i dont know were to find them, and need some recomendations.

1.- First what is better option for outgoing email, php or smtp.

2.- were i can set the throttle per email, i need to set it 10 seconds or more between emails hostgator only allows 500 emails per hour, so i want to send less so i dont exceed limit and stop receiving regular emails on all the acounts, or crash the site.

3.- were i can set it to send emails after 1 a.m. hostgator rules state that list over 900 emails must be send over 1 a.m. regular days (Off peak times qualify as all day Saturday and Sunday, and 1AM – 8AM Eastern Standard Time, Monday through Friday).

Thanx in advance for the help.

Regards