Outlook won't let me receive in my new email account in my MacBook Air - keeps giving the "invalid user name or password" message. Yet the new account

- lets me send;

- works on my iMac;

- it works in webmail; 

- has exactly the same configuration as my other email accounts on both computers - IMAP on the MBA, POP on the iMac;

- the same incoming/outgoing servers and ports (only the incoming ports are different on the iMac and MBA); on both computers for all three accounts I have to override the outgoing default port and type in a new one, which is the same on both computers;

- The SSL, Authentication and Security are the same for all three accounts on the MBA.

- I'm typing in the user name and password correctly.

And again, I can send from the new account on the MBA but I can't receive. The new account keeps the amber dot in the list of my three accounts. I've double- and triple-checked (more than that, actually) everything.

There is nothing I can see that's wrong, but there must be something. Any ideas out there?