Unable to delete emails from outlook mailbox

What is "Cached Exchange Mode," and how do you check for that? If I don't understand why I can't simply click on a message, then click on a trash-can icon, then see the message disappear, I certainly don't understand what Cached Exchange Mode mean, not to mention how to check for it.

I am using the ap on my phone. It worked last week, but not now. I do not have an administrator, and I have not changed any settings.

I don't know what it means, sorry.

I found out from another thread that the NEW Outlook is still in development (Beta?) and changes are being made in the background without users being informed.

The advice is to revert to the 'old' Outlook or, if you have Office 365, use Outlook through that programme.

Why can't I delete my read emails

If you're using NEW Outlook, it is still in Beta and background changes are made without notification.

I got a Microsoft Engineer to access my PC by remote link and he set up my 365 Outlook.

It's stable and is a better Client than New Outlook.