Please get rid of the pop ups notifications and switch to the native macOS style notifications.

It would be helpful to either completely move, or at least add a send button to the top bar when composing an email. When all of the actions except send are at the top it seems quite odd and confusing to have to go to the very bottom to actually send a message. Another idea is to possibly shrink the composure box so it isn't so far away.

"View Source" was an important tool for looking at the source (headers, body, servers, etc.) of a received message. It was in the context menu (right-click) but is no longer there. I could not find it in the menus either.

When sending an incorrect email add the ability to recall that email from all recipients as is possible with Office for Windows client.

Ooops - did we lose the 'Resend' option for sent messages?

After pressing the tab key to go out of the Subject field of a new email, please focus on the body of the email, not the Font and font size.

Current tab-key sequence: To --> Subject --> Font --> Font Size --> Body
Suggested sequence: To --> Subject --> Body

Have the ability to send an email to a group E.g. Interest Rate Changes and instead of sending emails back have the ability to turn into a chat underneath and in Teams. Like how Spark email does it at the moment with the Discuss email feature.

Would also be good for internal conversations on calendar invites, if someone wants to propose a new time or add info to the agenda. The calendar invite could become a Teams chat and files and chat could start around that meeting.

It would be nice if this view could be changed by the user. For example at the moment mine shows the event time, the duration, the event name and the location. The location shows the address which takes up 4 lines of type. While this is nice to have and is neatly laid out, my prference would be to toggle the location off with a nearby button or dropdown with toggle choices, to have some choice as to what is displayed here. The trade-off benefit is having more calendar events displayed.

There is no easy way to toggle the Sidebar, when extended/open, you need to go to the view menu but once collapsed/closed. there's a nice icon to extend it again.
This icon should always be visible to the user.

Outlook for Web condenses the conversation nicely; expanding only the most recent message and giving a preview of the others. You can then expand each previous message separately if you need more context.

I LOVE the Outlook web app and want it as a native macOS app.

I know I can tap in open in new window, but having to press it everytime is tedious and prone to mistakes

Add support for voting buttons.

Loving the new compact view for composing emails but would love to have the TouchBar controls like in the bigger view.

With the New Outlook for Mac, you seem to have removed the functionality to right-click on an email and set a reminder/flag/due date for a mail item. Can you please return this functionality? I found it especially useful for items that I could not act on at the moment but needed to follow back up with.

The ability to customise or use other keyboard shortcut schemes (e.g. Gmail) on the web app makes it 2x faster to process email. Please bring it to the desktop app!

Conversation threading should be a per-folder setting, so, for example, my Inbox could have it on and my Sent Mail could have it off.