The easiest way to send 500K emails

I am in the transportation industry and I have about 500.000 emails of carrier companies from USA. So I just want to send them an email about my service and my work...

I tried gmass but there is a limit of 500 emails per day - so it will take 3 years and also I can not use that email because when I hit the limit of 500 emails I can not send my regular emails anymore

easy ≠ high inbox rate

I think you can find the people who can send lots of email in a short time in Fiverr.