Why wont my Iphone send emails?

Im using an Icloud email and I was able to send emails yesterday. I can receive emails but whenever I try to send emails a thing pops up and says "cannot send mail A copy has been placed in your Outbox. No password provided. Please go to Mail Account Settings and enter a password" I've shut of my phone completely, logged out the email, logged out my iCloud, changed my password, and I've been looking things up. Please help.