Q: Cannot connect to Hotmail pop account OS x 10.9.5

change your username or password

if you are without a doubt sure everything is correct go to outlook.com and log in with the same exact credentials

it's possible the hotmail account may be older and the password policy may have changed but you are using a "grandfathered" password. If thats the case change the password to meet the current credential scheme.

Delete the password from Keychain Access (Applications/Utilities). While there, Keychain Access menu First Aid.

Keychain Issues - Resolve  see post by Kappy

Have you tried deleting the account and adding it back?

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