New Outlook vs. Outlook in Microsoft 365

One feature of the "New Outlook" I found very useful is the ability to send encrypted email messages.
Attempts to send encrypted email messages using the Outlook Classic desktop version were unsuccessful without a digital id.

Sending encrypted email messages using the "New Outlook" does not present any issues.
I suspect when using "New Outlook" to read an encrypted email message the message will appear normally without the need to verity a Microsoft account or use a one time pass key however, I have not verified this.

For clarity, I do have an active Microsoft 365 subscription.

Hello Gardis_SE

Hi, I'm Karl and will be happy to help you today.

First, some basics

The "new Outlook" is the replacement for the Windows 10 / 11 Mail, People, Calendar apps. It is essentially "Outlook on the web" (accessing an Outlook.com account via a browser), wrapped in an app framework with the added functionality to add external IMAP accounts. It is not (currently) a replacement for the Outlook desktop program (part of Office) which has a great many features not available in "new Outlook".

One of the benefits of using the "new Outlook" is that all devices connecting to an IMAP account will be able to see contact /calendar data when the "new Outlook" app us used. Something which cannot be done with IMAP accounts configured in the classic Outlook desktop program (.part of Office)

Things to look forward to in the new Outlook for Windows https://techcommunity.microsoft.com/t5/outlook-blog/things-to-look-forward-to-in-the-new-outlook-for-windows/ba-p/3975602

It will be a while before the "new Outlook" catches up to classic Outlook in terms of features so there is no simple "on size fits all" answer as to when one should be used over the other. For instance, POP accounts and PST files are not supported in "new Outlook". Thee is also no import / export functionality (currently) in "new Outlook"

If you have any questions, don't hesitate to ask, we're here to help you further if needed.