Oh My God Outlook 365 Sucks

Or am I supposed to call it “Office 365 Mail”?

If my session times out, sometimes it will actually show me my inbox for part of a second before asking me to sign in again. How secure is that?
Sometimes, no matter how many times I archive or delete a thread, it simply reappears in my inbox a few minutes later.
Every time I want to attach a file, it inserts two additional steps. First it asks if I want to get the file from OneDrive or from my computer (or it would, except it invariably fails to connect to OneDrive). After I select Computer and identify the file, it then asks if I want to link to the file in OneDrive or attach it to the message.
It forces you to click the pop-out button if you want to look at other messages while composing an email.
When my session times out, I return to a login screen. Fair enough. When I log in, I usually get an Error screen that says “We received a bad request.” It doesn’t even have the courtesy to offer me a place to try again, so I have to click my bookmark to try again.

This should have been very easy. The market requirements document could be three words long: JUST COPY GMAIL. Can’t Microsoft do anything right?

(For those wondering, I need to use Outlook 365 because my employer switched to it. Yes, I could use (Mac) Mail or real Outlook or something like that, but I prefer to avoid thick-client programs whenever possible, especially IMAP and POP email clients.)