Hey there,
After reviewing your project description it's clear that you want to learn setting up VPS and create SMTP server on vps to handle emails and create SMTP relay.
I'm very experienced with Linux Administration, DNS & SMTP server configuration.
I'll be happy to do this job for you.
Thanks in advance for giving the opportunity to working with you.
Have a good day.
Best Regards,
Serazum Munir.