Hello @gururajkoni69 ,
Sending this kind of bulk email for any campaign or marketing purpose you should use any third-party mail server to reduce server load and get some additional benefits.
This is why: https://www.extendwebservices.com/blog/bulk-emailing
Just let AEM server to-server content only. For a few emails sending like form submission, notify admin is perfectly fine from AEM.
However, if you want to strict your requirement you can follow @rampai answer.