How to Disable single click to open email in New Outlook?

I've been to numerous forums where people are upset with this functionality, but I haven't come across the real fix you're looking for. Until that functionality exists, here's the workaround I use:

Turn reading pane on with bottom placement and shrink the reading pane down as small as it allows. It doesn't feel like it's in the way, and I can single click through everything without losing my inbox view. And I can double click to open the email in a new window.

Hope this helps ease your frustration!

It is driving me nuts as well - i assumed there would be an easy fix

The reading pane really has nothing to do with this issue. You can have the reading pane on or off to display the email within that pane of the main Outlook window. The issue is having the email open up to a second window on single click vs. a double click.

I just found this issue too (now moved to using the web based mail only).

My conclusion so far until they fix it, instead of single click, right click and go direct to the options I was probably after anyway.

I single click because I want to delete/Mark Read something without reading, and found these options are immediately availavle in the right click menu

You can also change the quick clicks to add the "delete" "move" or "flag" option so it is shown when you hover over the message in your inbox, which provides you with the option to just click that icon to delete something, or archive something, without the need to right click. Still hoping they fix this at some point, because I do continue to open a lot of emails that I don't want to open, but this update to the inbox has helped.

Well said, completely agree.