We highly recommend configuring your iPhone to sync your various IMAP folders. Below are the steps to do so.

1. Within the "Mail, Contacts, Calendars" settings window, select the account that you just added.
2. Under "IMAP", select your Account.



3. Within the accounts settings, select "Advanced":



4. You should now be at the screen below:



5. Under "MAILBOX BEHAVIORS", select the first item ("Drafts"), then select the appropriate folder under "ON THE SERVER". Here's an example for the Drafts folder:



6. Now repeat this step for "Sent Mailbox" and "Deleted Mailbox". Ignore the "Archive Mailbox", it won't be used.
7. Last step! Make sure "Deleted Mailbox" is selected under "MOVE DISCARDED MESSAGES INTO". This will ensure deleted messages go to the Deleted Mailbox folder.
8. That's it! You should be all set now! Enjoy your email.