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