Website blocked by ATP Safe Links in Office 365.
Office 365 Advanced Threat Protection has encountered an error.
Error: The page that you are trying to access cannot be loaded while accessing the URL from email or Office documents.
The Office 365 Advanced Threat Protection (ATP) could custom block the URL when you click on the URL in Outlook or Office applications, To bypass the ATP you need to custom ‘do not rewrite’ the list of URL.
For more information, see: Set up a custom do-not-rewrite URLs list using ATP Safe Links
A 'do no rewrite list' in the O365 ATP Safelinks policy and add an exception webex.com domain. For help, see: https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/set-up-a-custom-do-not-rewrite-urls-list-with-atp?view=o365-worldwide