I just can offer you the link to 'Settings' in my signature. See section [MailScanner]
I do not use YahooPOPs but you can search the board to have more information.
Probably:
DefaultPopServer=pop.servername
DefaultSmtpServer=smtp.servername
DefaultImapServer=
SmtpListen=127.0.0.1:26
PopListen=127.0.0.1:111
ImapListen=127.0.0.1:143
On Outlook, you should configure each email account to listen 26, 111, 143 and not the defaults.
Note: DefaultPopServer and DefaultSmtpServer would be better that way and not 127.0.0.1:port number