I have successfully updated Manager, and re-entered my email credentials twice and updated.
When I try to send a test email. it spins for a while and then eventually just comes back to the settings page with no error or success msg.
Post a screen shot of your email settings page. You said you had read the Guides about emails. The troubleshooting Guide tells you what information to provide if you have a problem. You have not yet given that information.
I just tried changing the port, and 25 was the only other option listed so I used that. After updating the settings, the test email went out correctly. So I think it is solved unless you know some reason that won’t work.
I tried all the suggestions, on my gmail account, set up password for Manager etc. managed to send a test message, but then could only send to gmail addresses. Went back to my .nf account, set up again, and now all working for me, goes to any email address I select.