I have a home lab setup for testing and developing solutions in Office 365 hybrid configurations with on-prem systems. The only real issue I've run into so far is that my ISP blocks outbound port 25 to combat spam. However, Microsoft requires port for hybrid mail flow to work between my on-prem environment and EOL. I've gotten around this so far by getting a VPN provider that allows special ports like 25 and setting up an OpenVPN gateway in my router to forward just that port 25 traffic over the VPN tunnel. Success! BUT - I'd like to investigate options for using Azure networking itself to route this traffic for my home lab, again just port 25.
So my question is this, does anyone have any tips or guidance for the following:
1. Is it possible to create a VPN tunnel with Azure where SMTP (port 25) traffic from on-prem can route through Azure to O365 EOL?
2. Is there a solution that avoids the need to run a VM inside of Azure on the VPN gateway/network?
3. Is it possible to use a static IP with this solution to avoid having to reconfigure my on-prem tunnel every few months when the IP rotates on the azure side?
4. minimizes cost
I am using pf-sense and understand how to create VPN tunnels and know that S2S VPN in Azure is definitely doable, but my question really has to do with routing specific traffic through Azure to O365 EOL. If anyone has done this or understands what I'm after, I'd love to hear your thoughts and feedback on how I might be able to make this a reality. If I can get an Azure VPN tunnel to route my port 25 traffic, then I won't need the other VPN provider anymore and can cancel that subscription in favor of Azure.