It will be a while coming, but on the Office 365 roadmap, Microsoft announced their intention to bring the ability to send email from alias addresses to the Outlook Web App.
Microsoft notes that the ability to send email from a proxy address (aka alias) other than the sender’s primary SMTP address is useful in multiple scenarios, such as mergers and acquisitions when you need to send from multiple branded domain names, or sending on behalf of a team or department, like [email protected]
The feature, which is targetted only for Q4 2020, will let users choose the sender or FROM from a drop-down list right within the compose pane. And when the recipient receives that message, the FROM and REPLY TO will show that alias, regardless where the recipient’s mailbox happens to live.
Microsoft recently announced that it has begun turning the Outlook Web App into a progressive web app, allowing users to install it on their PC or Chromebooks as if it were a normal app. Like PWAs, you’ll be able to view your emails offline, receive notifications, and essentially have the app appeared windowed.
Microsoft is also working on a Message Recall Feature which would allow Microsoft’s cloud email to retrieve emails not yet opened by the recipients, regardless of the email client they use.