Your Outlook may be configured to use SSL or incorrect POP3 port.
Please try the following steps:
- In Outlook, click Tools => E-mail Accounts
- Click View or change existing e-mail accounts and click Next.
- Click the account of type POP/SMTP (Default) and click Change.
- Click More Settings.
- Click the Advanced tab.
- Make sure SSL is not used and POP3 port is 110 (default). Click OK. In the next window, click Next and click Finish.