1) Open the iOS device

2) Tap Settings.

3) Tap Mail Contacts and Calendars.

4) Tap the account that you are wishing to sync.

5) Select the email address once again to enter into the preferences for that account.

6) Tap the Advanced button at the bottom of the screen.

7) This is where we will now have the option to sync up our Deleted, Sent or Drafts folders. The process is the same for all three of the folders.

Tap Drafts Mailbox to setup the syncing for draft messages.
Tap Sent Mailbox to setup the syncing for sent messages.
Tap Deleted Mailbox to setup the syncing for deleted messages.

8) In the next menu simply select the matching folder name from under the On The Server section.

Sent Mailbox = Sent Items
Drafts Mailbox = Drafts
Deleted Mailbox = Trash

Thats it! You should now be syncing between multiple devices.