sending mail via SMTP server

I am using a script to send mail directly to the SMTP socket. It seemed to work OK for the first 200 emails - then stops sending them. Is there something I'm missing here? As you may be able to tell I'm trying to come to grips with how sockets/SMTP works. Is it like this... 1. I open the socket to the SMTP server 2. I fire the mail through - a few thousand emails 3. I close the socket Do I have to close and reopen the socket every few hundred emails? Regards, Matthew Delmarter