How to set up an IPhone device

Basic Setup

Following this guide you shall be able to configure your mail account on IPhone:

http://www.emacconsulting.com/email/how-to-create-imap-mail-account-on-iphone

    NOTE: Although the password entry for the outgoing mail settings usually says "Optional", it isn't. 
          You will need to enter your username and password.

We also recommend that in the main email settings you enable Ask Before Deleting"

Advanced Setup

Source: http://5thirtyone.com/apple/how-to-proper-gmail-imap-for-iphone-apple-mail/

Steps to properly configure IPhone Mail client so that Sent Mail, Deleted Mail, Drafts are reflected properly after syncing (back to the server):

1. Open Settings > Mail > [Your account] > Advanced
2. Select Drafts Mailbox > On the Server > Drafts. Return to the Advanced view.
3. Select Sent Mailbox > On the Server > Sent. Return to the Advanced view.
4. Select Deleted Mailbox > On the Server > Trash. Return to the Advanced view.

    NOTE: Also see Auto Purge.