Office 365 Useful links
Here are a number of useful links that aren't well publicised that Office 365 admin should have in one place: https://testconnectivity.microsoft.com/ - Connectivity testing https://securescore.office.com - Secure Score O365Ports&URLs - All the ports and FQDN required for Firewall access and DNS https://channel9.msdn.com/Shows/Mechanics - Microsoft Technical blog https://channel9.msdn.com/Shows/o365update - Latest updates and features for O365