Hello sir, i know i am new to this platform but i can assure you i can provide the best service you require.
For your project i will use a script that you can run on the terminal specifying your data file to send bulk emails based on an html template.
There are several options but the top bulk email sending service will be AWS SES (simple e-mail service), its fast, reliable and cost effective, you can send upto 42000 emails daily for free, also check out its pricing its pretty affordable and most importantly reliable.
If you have any specific service you would like to use then we are always open for such demands, feel free to leave me a message and then we can continue from there.
Thank You
Regards,
Reshab