With the reading pane on the right, allow additional columns in the message list
This was lacking in the original Outlook for mac, but still think it needs to be done. I like placing the reading pane on the right. With the message list, I'd like to see the option of adding additional columns to quickly sort by. This is one of the features I use so heavily that I still find myself using Windows-based Outlook on mac.
Being able to collapse the sidebar and see favorites folder is also helpful as it allows you to show:
- collapsed sidebar with easily accessible main folders (inbox, sent)
- list of messages with columns
- preview pane on the right