When sending an email from your iPhone running iOS8, or an earlier iOS version, and you get an error message “A copy has been placed in your outbox. The recipient was rejected by the server because it does not allow relaying” there is a very good chance you need to check your outgoing mail server settings. Here’s how:
1. Go to Settings -> Mail, Contacts, Calendar and tap on your email account.
2. Tap on “Account,” then go down to the “Outgoing Mail Server” section and tap on “SMTP.”
3. Tap on your Primary Server
4. Even though it says “Optional,” fill out both user name and password under Outgoing Mail Server.
5. Tap “Done” in the top right to save your changes.