Allow Office for Mac users to set the default meeting duration to end early, i.e. 25 min for 30 minute meetings and 10 minutes less for 1+ hour meetings.

This feature is already supported on Windows client and on GSuite.

In the new version of Outlook for Mac, the conversation view is too hard to follow when multiple "active" emails are in my inbox. The mix of archived emails, sent emails and more makes the email chain crazy to follow. Please add the option to hide emails not in the current folder (i.e. when I'm in the Inbox View, I see all items in the conversation that are also in the inbox). Then like in the old version of Outlook, you can have the button to show all.

Ability to export signatures or have the signatures centrally stored in 365 cloud. This is really quite necessary for migrating users between machines. @LukeHamburg has summed it up perfectly here:
https://answers.microsoft.com/en-us/msoffice/forum/msofficeoutlook-msomac-mso_o365b/outlook-2016-mac-signatures-how-to-export-import/1bfa4b27-4ea4-46c1-8263-c92ae557b277

Separate the calendar function into a separate app so we can see our calendar side by side with our email, or just open one or the other. Often, I want my calendar open but not my email to minimize distractions.

Please add the menu bar above emails, so we can easily sort through our tabs - FROM/ SUBJECT/ RECEIVED/HIGH IMPORTANCE/ATTACHEMENTS etc.

Move search bar within Outlook back to its old location. The new location of the search bar is inconvenient and not intuitive, the search field should be closer to the emails themselves instead of excommunicated to the blue bar at the top of the netherworld. Not sure why anyone thought that would be a good idea or that anyone would have asked for that. Please move it back within the body of Outlook so it is closer to the email content that needs to be searched.

It should be extremely obvious to the user when a message was not sent for some reason (attachment size, etc)–not just by the number of messages indicated in "Outbox". This directly impacts the reliability of the service and my reputation as a business owner.

Make the new Outlook available to users of Exchange OnPremise again. Or at least: let us know whether it will ever come back or not. I used to work with it just fine (fast insider), and then suddenly the support stopped, with no explanation whatsoever.

whenever I add an (inline) image to a message, outlook automatically generates Alt Text to helpfully describe this graphic. please provide a way to disable this. I share design visuals many times a day, and this description is almost never even close: eg a recent effort was tagged as being 'A parrot'. which it really wasnt

I want to be able to pass the contents of mail messages in a certain folder to a script. I control the script so I can handle them how ever you want to pass them. File handle, stdin, command line option, etc.

Even the option to store that folder in MBOX format so that I could just tail -f the tile would work.

You have the option to recur monthly on the first, second, third, fourth and last [Monday, Tuesday, etc.], but some months have 5 Monday, Tuesday, etc. Selecting last may put it on the 4th which may not be correct. I use the outlook calendar for my boss so they have access to their schedules from their phones when there aren't near a computer.

The calendar should appear so you can quickly choose a date, rather than scrolling up and down on days and months. Same for the time... Suggest 09:00, 09:30, 10:00. 10:30 etc.

The contact within the company had organizational structure within contacts that allows you to look at an individual's direct reports as well well as who they report into based on the Active Directory. The new Outlook design released in Oct 2020 doesn't allow to look up organization. This is still available on the older look in Outlook or Microsoft Teams.

Add a "Send Sent Item To" button in Outlook for Mac

We use encryption regularly. Outlook regularly crashes when trying to open an attachment in an encrypted email. Sometimes I will have to try to open the attachment 3 or 4 times before I'm successful (with Outlook crashing each unsuccessful attempt). If I have any draft emails that have not been sent when Outlook crashes, they are often not autosaved. Please make Outlook more robust with encrypted email.

Please add the option to permanently delete emails without confirming

There should be an option to show Titles before name of sender, or at least to give them more prominence.

Most of the time knowing the sender adds very little information, the title is usually much more informative. It's very hard to go through a lot of emails this way.

Even the web version has this feature. Every mail client I remember since the 90s has this feature. From the message I got from support even the mac version had it at some point.