Sending Emails with High Speed

Hello friends,
I want to send multiple emails with high speed. I am sending a newsletter on daily basis to around 4000 contact-IDs. I developed VB.net code for sending emails through THREADS. My threads are sending Emails to my contacts. But the problem is the speed is slow. I wanted to send emails with high speed and with less email bounce ration.
Any help is strongly awaiting.....


Thanks
Sameer

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