Not everyone uses or wants to use OneNote or Customer Manager, and if you’re not using these applications, these buttons take up valuable space in the ribbon, hiding other more useful buttons - e.g. Read/Unread. I appreciate this issue is linked to screen size, and is therefore probably not an option on larger laptops or desktops screens, but it is a significant issue on smaller laptop screens.

When I raised this with MS Support, I got the following response: "we are able to reproduce it on our end and we have a confirmation that this is expected behaviour for OneNote integration. This was known to us recently. Since it's add-in based now, there is no option to enable or disable it manually and it would auto-deploy even if the add-in is deleted. The add - in is auto - deployed and Outlook for Mac contacts the server to get the available add - in for the mailbox"

In Calendar, normal mode, “busy” appointments have a blue line, which has a good contrast with the white background. “Free” appointment have a white line, which “blends” with the background. This gives good visual experience on what is really important or what’s in the calendar just for information.
But when switching to Dark mode, the colours are the same, so a Free event really pops out of the Calendar, as if it was something very important, and a blue Busy event remains in the background.
Same feedback for the events main background colour: grey in Normal mode, Blue in dark mode. I had a lot of Blue Categories, now I had to change them another colour as they would blend into the Dark mode.
But when I get to OWA, which has no Dark mode, I get all the new colours…
It would be great to have a different set of colours (for both Categories and Busy/Free/OOO) to display in the two modes.

There is an issue that others seem to be having when using Outlook on a late 2015 iMac. We have 3 employees at my company with late 2015 Retina 5K iMacs (27", 3.2GHz Intel Core i5 Processor and 8GB 1867 MHz DDR3 Memory) whose screens will flicker and turn white/black, but when they restart it fixes the issue for a day. Then it happens again. It seems to happen when Outlook is open, which we are constantly using, and from another forum, it seems to be happening to many other people with this same exact model iMac and Outlook. Apple suggests resetting the SMC and the NVRAM (which I have done for all computers) and then running a diagnosis. I have not run a diagnosis yet, but from what your forum says, it doesn't seem to come up with anything anyways. Please look into this! Thank you!

I had Outlook 25 years ago, it was professional. I changed to Mac and have been getting by with their software for over 15 years. I just tried Outlook again and found it to be simplistic and very restrictive. It seems to be designed by children. I have 4000+ contacts and can't import them to Outlook because of its serious limitations. With Outlook, I can't include a business's website in the Address Book (“People”). I can't even make a contact for a business name like Microsoft. This is shocking. I also don't like my Calendar separated by my email addresses as Outlook does. I am one person with one schedule and don't split up my body and its meetings according to my email addresses. And, when creating an appointment in Calendar, I cannot make more than one reminder and am restricted to Calendar’s predetermined times. I live by my repeated custom appointment reminders. I am returning Outlook and hope one day it will improve.

Sort the size of the "Message Sources" cache.

Mine is 18GB, while the "messages" folder is less than 1GB and "Message Attachments" is less than 5GB. Why is "Message Sources" so big?

I only discovered this because Outlook had made several backups and filled my Hard Drive. I had to do some detective work to find where all this data was that was filling up my HDD and I eventually discovered the Outlook folder stored in the hidden ‘Library’ on my MacBook had around 90GB of files. This included the ‘Main Profile’ which held around 25GB and several backups of this which contain between 5GB and 25GB each.

Tech support didn't even know what this was or how it was created and I got some very vague answers as to how to deal with it, including some 'solutions' that did nothing to alter the size of the "message sources" folder.

For Outlook to be taking up 25GB of HD space when my actual messages and attachments take up less than 6GB is a little ridiculous, no?