Hey there,
After reviewing your project description its clear that you are having issue with your Dkim and you also need to setup rDNS matched with your smtp banner.
I'm very experienced with SMTP Server Configuration, SMTP IP Rotation, SMTP Authentication (SPF, Opendkim, Opendmarc) installing and configuring.
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.