I am sorry, I didn't intend to confuse you. It's my English!
Since, you received an error such as the following, you need to have SSL checked for POP/Incoming Mail Server in your Email Client (Outlook).
Once you check SSL, it shouldn't complain with this error. Outlook will probably ask you if you want to accept the server certificate. Say, Yes, here.
Log onto incoming mail server (POP3): Your e-mail server rejected your login. Verify your user name and password in your account properties. Unter Tools, click E-mail accounts. The server responded: -ERR only valid after entering TLS mode
Your email should flow in now.
Regarding the second error:
You are receiving the second error while trying to send email.
Send test e-mail message: Your e-mail server rejected your login. Verify your user name and password in your account properties. Under Tools, click E-mail accounts.
This, too, looks like SSL is not checked for Outgoing Mail Server. Can you confirm?