Hey there,
After reviewing your project description its clear that you want someone to create a SMTP server for you and you want to use that SMTP server with your gmail account to handle Incoming and Outgoing Email and you also want explanation about how does it work.
I'm very experienced with SMTP Server Configuration, SMTP IP Rotation, SMTP Authentication (SPF, DKIM, Dmarc, rDNS), DNS, System Administration, SMTP Server Troubleshooting and fix errors that will prevent you from sending and receiving emails.
So the job is to install SMTP server and once you want to receive emails also so I need to setup IMAP or POP3 also and I'll be very 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.