For the next several weeks (and months?) I'm evaluating at least a dozen open source and commercial #email apps.
Now, I'm honestly not saying this because I work at @thunderbird, but the new #Outlook is a buggy mess within the first 5 minutes of use. I'm quite surprised that "Switch to New Outlook" toggle is even there.
My Gmail account requested re-authorization twice, and switching off Focused Inbox completely zapped everything from the message pane, and I can't get it back.
