Background: I have an Azure Front Door setup with a custom domain name. In the DNS settings for this domain name, I have added CNAME records pointing to the Front Door URL. That is, there is one CNAME record for www.example.com and another one w/o the www (i.e. example.com). It was added correctly in Azure and everything was working fine.
The Initial Problem For whatever reason, the CNAME record example.com (that is, no www in front) could not be added due to a conflict. When it was added emails were not being delivered correctly. Upon deleting this CNAME record, emails are working fine.
To overcome this, I added a redirection rule in Front Door. When users type "example.com", we are directing them to "www.example.com".
The Current Problem This redirection is working fine in about 75% of the browsers. We are getting a lot of users complaining that typing "example.com" shows server not found. However, typing "www.example.com" is working fine.
Here is the redirection rule.
Any idea why this is happening? I would be eternally grateful if someone can please shed some light. Thank you.