It is, sadly, not so easy to delete a bunch at once: you still have to delete them individually. Can things get much worse? They can.
If you get lots and lots of mail, deleting all the messages once might not be enough. You still have to remove them from the Trash folder, too, or your iPhone Mail fills up.
Fortunately, at least the second round of deletion can be saved. Set iPhone Mail to remove all deleted mail after a day in the Trash and it takes care of cleaning up.
Make iPhone Mail Keep Less Deleted Mail
To tell iPhone Mail to remove deleted messages from its store faster:
- Tap Settings on the iPhone's Home screen.
- Go to Mail, Contacts, Calendars (or just Mail).
- In earlier versions of iPhone Mail:
- Tap Accounts.
- Tap the desired account.
- Select Advanced.
- Tap Remove.
- Make sure After one day is selected.
- Tap Save.
(Updated September 2012)