A change made to fix a problem in Exchange Online introduced another problem in that service domains started to show up as prefixes in the data returned by PowerShell cmdlets. Microsoft has reversed the change, but the way things happened creates some questions.
You can use the Send-MailMessage cmdlet in a PowerShell script to send mail messages via Exchange Online. And sometimes your IP address might be listed as a spammer, which is bad. All in all, authenticated client submission seems best.
A question asks how to remove a bunch of emails from a shared mailbox. You can use OWA to do the job, especially with its Cleanup Mailbox option, but perhaps some administrative action is needed.
A new Exchange feature rolling out inside Office 365 allows meeting organizers to block people forwarding their meetings to all and sundry. The latest versions of OWA and Outlook 2016 click to run support the UI for the feature and blocks are built into Exchange Online and Exchange on-premises servers to stop blocked meetings sneaking through.
Hanging on to old email habits is a bad idea, especially if you use a cloud service like Office 365 where Microsoft introduces a steady stream of new features. The worst bad habit is password sharing. It’s time to stop this now.