Error message:
Server denied POP3 access for the given username and password. Please contact Microsoft's support team for more information on POP access. Server returned error: "Authentication failure: unknown user name or bad password. [Error="ProxyNotAuthenticated" AuthResult=0 Proxy=PS1PR0201MB1756.apcprd02.prod.outlook.com:1995:SSL]"
Found out that Hotmail had turned off POP3 access.
To turn it back on, log on to Hotmail, go to Options > Accounts > POP and IMAP.
Under POP Options, select "YES" for Let devices and apps use POP.
Log out from Hotmail.
Go to Gmail and try connecting again.
Ref: https://productforums.google.com/forum/#!msg/gmail/r788QIQbV00/oyDVt1dfNQAJ
