as a tip u put first email then the rest 499 u put it as bcc and fire all at once then u move to next gmail account and send again ...
NOW Still working on my project... hope in 2 weeks will be rdy :P wroking now at the proxy option...

What my script do? allow send inbox 100% mails by using gmail accounts after i finish my work on script i will try to add a gui interface that will allow me to send from an website and if everything will work like i want i will make it public with a /month membership :P will be big discount for blackhatworld members i will update progress soon about my project:P
The web interface will ask for users to input the mailing list, a proxy list then the gmail accounts used to send email and email body...