Which is the best white-label cold mailing platform?

I want to start my own email marketing agency as well as sell my own email marketing tool.
But, I have very limited technical knowledge in setting up an SMTP server and overcoming its complexity.
Though I explored some (ready-to-use) white-label tools to resell, they are not suitable for my (entry or small business) audience.
Can anyone please suggest the best white-label cold emailing tool that can send up to a million emails per month?
All suggestions are welcome.

Something on CodeCanyon would work for this case. Look at the PHP scripts and research any of the few Email Marketing ones.

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I don't think that you'll find such an offer. You can find a white label platform but no one can truly guarantee the 1M.