iPhone Won't Delete IMAP emails

what setting for deleted Mailbox shows on the iPhone in Settings:Mail,Contacts,Calendars: (test account name): Account Info: Advanced: Deleted mailbox ? Should have in "On the Server" - Deleted Messages with a check next to it.

i'm having the same problem but i don't have the option of selecting "On the Server".

i click "Deleted Mailbox" in advanced settings and the "On My iPhone", "Trash" i checked. below that is "On the Server" and below that "Inbox" but these boxes are shaded out. i can't select anything on this screen.
any suggestions?

Jackie
Do you have an IMAP capable email account? If you have a major ISP like AT&T or Comcast, they haven't typically supported IMAP to date. Gmail does and if you have a private domain, most hosting providers support it.

If you have an IMAP capable email account, then setup the account, then go into mail inbox and hit the refresh button once. The go back to settings > mail, contacts > calendar and then click on your new IMAP account. Scroll down to the bottom and go into advanced. At the top will be an area titled "Mailbox Behaviors" with a Drafts Mailbox, a Sent Mailbox and a Deleted Items mailbox. Click on each and select the "On the Server" folder that corresponds with each one. For example, for Drafts, click on the Drafts folder on the server. Sent may be mapped to Sent Items, Sent Messages, etc. Hope that helps

here's what worked for me.

in the advanced settings, i had to add the text "inbox" (without quotes) to the imap prefix.