I am the technical lead at a small startup that provides a video library to corporate clients, with a Microsoft (.net/IIS) stack. One of our features is providing each client with its own subdomain based on their username (client.oursite.com). In the past, we were manually setting up CNAME records for each client, however, it was getting impossible to manage, so a couple months ago, I added a wildcard A record (for a unique IP), bound that IP to the site in IIS, and handled any custom logic in the application. Everything has been working very well with this setup. However, I received an email from the company hosting our exchange server, asking us to remove the A record as they said it would cause issues with outlook. After several email exchanges, I received the following
We are providing hosted Exchange services to our clients. What that effectively means is that all of our hosted Exchange clients are not a part of our Exchange AD organization. The only way to support autodiscover in the hosted scenario by Microsoft is to have properly configured SRV DNS record in place which all of our hosted Exchange customers do have. For this setup to work A autodiscover record must not be present in the DNS at all.
I have no expertise in email administration, but I find it hard to believe that no one has ever used hosted exchange while having a wildcard A record in their DNS. All of our MX SRV records are correct and point to the email host's ip. Furthermore, there's no way we can go back to manually adding CNAME records. Is there any workaround here?