Sending has nothing to do with receiving.
No matter if you're using IMAP or POP3 for receiving messages, sending always uses SMTP - a whole different protocol - and a whole different server (may be running on same hardware or same address, but conceptually, it's different).
If you can elaborate on the sending issue, maybe we can do something about it. The best way to do that is to capture the issue in a debug log (link below).
But to also answer your original question -- remove the account from Aqua and add it back, using Manual account setup button.
I don't know any apps that can switch between IMAP / POP3 / EWS, and this includes the big ones like Outlook and Thunderbird.