You will not have issues until Microsoft upgrades your account to its new look. I have four accounts. I use POP3 on all of them. Yesterday two of those accounts failed to connect.
Code:
POP3< -ERR Authentication failure: unknown user name or bad password. [Error="ProxyNotAuthenticated"
AuthResult=0 Proxy=HK2PR01MB0322.apcprd01.prod.exchangelabs.com:1995:SSL]
*** error occurred on authentication
*** Authentication failed.
As part of this change Outlook.com decided to disabled POP access.
So... you have to re-enable it. There is also a server change. The server I used until the change was "pop3.live.com" the new server is "pop-mail.outlook.com" (the "pop3.live.com" still works). I noticed that both IMAP and SMTP servers have also changed. Ports and encryption methods have stayed the same.
Today another of my accounts failed with the same problem. Logging in and re-enabling POP corrected the issue. I decided to change the servers on my last account that is still using the old interface, it works fine with the new severs but I suspect that POP will fail once that account is upgraded, and I will have to logging via the web to "fix" it.
If you using IMAP or the web interface this will probably not affect you.