This suddenly started yesterday 3/4/2020.
I have 3 email accounts on my android Outlook app. Outlook.com, Google, my ISP's. The problem only happens with my ISP (comcast.net, IMAP).
Till yesterday night, I can send/retrieve emails from the same server without an issue with Outlook app.
First I noticed Outlook requested to re-enter email password. But it failed. So I deleted account, then added. Failed. I even removed Outlook app and re-installed it. Failed. Google and Outlook account are just fine.
I didn't change anything from my side. I can access Comcast email from Web/Windows 10 mail and even from the same phone using Samsung standard email app.
What was changed and how to solve it? I can use Samsung standard email app but I like Outlook.