Almost any advice out there is to use a service for sending mail, but our volume would make it too expensive, even with elastic email which is fairly cheap. On top of that I would like to scale out during sending of the mail for performance purposes
What I would prefer is some sort of VPN setup so our IP addresses that we use now can still be used as the public IP. That way we should be able to send mail on azure using our on-premise server as gateway only.
Second option is using a SMTP relay on windows, but that way we are still throttled by the SMTP capabilities of our server I think?
To be sure, I’m not some spam king. Our users receive our mails for over 10 years now without complaints.