I have an iphone 4, using the default email browser, using my icloud email address. I can receive emails, but can not send them. My service is only talk and text, no data, so I depend on wifi alot. What am I doing wrong?
Usually the easiest method to solve problems with email accounts is to remove them and set them up again.
You could also access the account through iCloud using a browser, except for Safari on your iPhone, and see if you can send emails there. Maybe it's possible to look at the settings there, if this doesn't work either.