Hotmail and Yahoo allow POP / SMTP free of charge, so using MailWasher isn't an issue.
PPRuNe mail doesn't - it's chargeable - so unless you pay to upgrade you can't.
For Binos, POP is Post Office Protocol - the mail server acts as a post office from where your email client collects mail. SMTP - Simple Mail Transfer Protocol - allows sending of email from the client.