I'm Desperate For Some Help Please.

I tried to clean up my mailbox on my MAC, and now the Mail App is not connecting to the internet. My WIFI is connected but Safari and Google Chrome are not connecting.

I am running macOS High Sierra v. 10.13.6

In the Mail Program, when I click on Connection Doctor, it says that the Hotmail SMTP and iCloud SMTP connection and login to server succeeded, but the Hotmail and iCloud IMAP can't connect. I get this message:

Could not connect to this IMAP server. Check your network
connection and that you entered the correct information in the
Account preferences. Also verify that the server supports SSL. If it
does not, deselect the "Use TLS/SSL' checkbox in the Server
Settings tab of Account preferences.
(I don't know what this means)

Also in the Mail Program, in the Margin on the left, the Inbox and Hotmail folders (and lots of other folders have an exclamation mark inside a triangle next to them.