On or around February 1, 2019, a major upgrade will be made to the Domain Name System (DNS), that may impact the ability of your website and email to function properly.
As reported on the DNS Flag Day site:
The current DNS is unnecessarily slow and suffers from inability to deploy new features. To remediate these problems, vendors of DNS software and also big public DNS providers are going to remove certain workarounds on February 1st, 2019.
The site offers a test to determine if your domain will be impacted by the changes. With only days remaining, now would be a good time to visit the page, test your domain name, and call your IT support should the test report problems.