When you initiate sending a message from another iPhone application, the message is sent from your default email account. Examples are sending a photo from Photos or tapping a business’ email address in Maps.
To set the default email account
- Set up the Yahoo! Mail within your Apple iPhone. Read the article "How do I set up access to Yahoo! Mail on my iPhone?" for details.
- From the Home screen, choose Settings > Mail > Default Account, then choose your preferred Yahoo! Mail account.