Messages stuck in the Outbox in iOS Mail
If messages are stuck in the outbox, you'll need to delete them before you can send new email.
- Launch the iOS Mail app
- In the top-left, tap either Mailboxes or your Yahoo Mail account name.
- Tap Outbox.
- Tap Edit.
- Select the messages you want to delete.
- Tap Trash.
Try to send another message. If it gets stuck again, learn more ways of fixing this.