Multithread with net/smtp?

Hi,

I’m working on a project to send a massive number of emails as quickly
as possible.

At first, I used the net/smtp module to send emails with single
thread. The speed wasn’t fast enough for me, at about 3 messages per
second.

I then tried using multiple threads, with each thread starting a new
SMTP session. All of threads send emails simultaneously.

I had hoped this will speed it up a lot. But the result was
disappointing. With 10 threads, the speed is just a tiny little bit
faster than the single thread version, while I was expecting maybe 7-8
times faster.

My OS is Windows 2000. Am I missing something here? Any suggestions
would be appeciated.

Lei Wu