Microsoft implemented stricter fraud detection checks in Office 365 and Exchange Online Protection and unauthenticated messages are automatically marked as spam and moved to the Junk Email folder.
Use the Remove-CalendarEvents cmdlet to cancel and remove calendar events organized by a former employee.
How to Copy events to other calendars using Copy to My Calendar, a macro, or Microsoft Flow.
Can you create an appointment or meeting using contents of an email message in Outlook on the web?
PST Collection Tool from Microsoft is the successor to the PST Capture tool. In addition to helping administrators collect PST files in their network, it can also lock down their usage.
What to check when the Focused Inbox is enabled for the account but isn't available in Outlook.
A new feature in Office Groups (available in Office 365 Exchange Online) is the ability to use 'Send as' or 'Send on behalf of', just as you can for shared mailboxes.
Outlook on the web's new feature: Undo Send. It gives you a few seconds (up to 30 seconds) to change your mind.
Mailbox quotas for E3 and E5 accounts is increasing to 100 GB, with all other Office 365 Exchange mailboxes remaining at 50 GB, including Business, E1, shared, resource, group and public folder mailboxes.
How to enable auditing on an Office 365 mailbox.