I have 2 site which are hosting the exchange servers 2013.
Primary site/active site - has exchange server and also have Hybrid server ( servers part of hybrid configuration)
DR site - two exchange servers.
My Mx records are pointed to office 365 and all e-mail is received by the cloud and it sent to the hybrid servers in the primary site and hybrid servers distribute them to the servers on which mailboxes are hosted.
Primary site cannot access DR site (NO mail flow)
My organization comes up with a plan of load balancing between the two site so when the Primary Exchange site is down emails should flow to the DR site.
They are smart hosts on each site and these smart hosts are can be pinged from internet.
My organization now wants me to validate mail flow from office 365 to DR site. I tried to create a new connector from office 365 to smart host at DR site and i was able to pass all the configuration steps but i failed at the send email step. i checked
with my network and firewall team and they said port 25 and port 443 are open till the exchange server.
I also noticed that the mail sent from office 365 as a validation is using the smart host at the primary site even though i mentioned the smart host at the DR site during connector configuration. Is there any other way i can validate the mail flow?