problem deleting emails
When trying to delete an email on my new iPhone 4s (just came over from BB), I click on "edit", click the circle next to the email I want to delete, click the red delete at th ebottom and I get a message that says "Unable to Move Message. The message could not be moved to the mailbox Trash." The other way to delete, look at the email and click the trash bin at the bottom of the screen, gives me the same message. I know I can move these emails to the trash bin manually, but then how do I empty the trash bin?
So, 1) what do I do to get the emails deleted directly and 2) how do I empty the trash?