All IMAP clients differ, and you can configure your mail client’s settings to best suit your needs. However, to work optimally with Gmail, you may configure your iPhone accordingly.
From your mail account’s Advanced Settings:
Deleted Mailbox > On My iPhone > Trash
Deleted Messages > Remove > Never
With these settings, messages deleted from the web interface will show up only under your [Gmail]/Trash folder. In addition, messages trashed from the iPhone will show up under your iPhone Trash folder and your [Gmail]/All Mail folder.
To avoid inconsistent deletion behavior, please manually configure your iPhone.
Instructions for Manually Configuring Google Apps Email Addresses
These setup instructions are for Apple devices running software version 4.0. To configure the ‘Mail’ app on an Apple device for access to Google Apps email, just follow these steps:
- Make sure you have enabled IMAP in your main Mail settings
- To enable IMAP in Gmail, sign in to Gmail.
- Click Settings at the top of any Gmail page.
- Click Forwarding and POP/IMAP.
- Select Enable IMAP.
- Click Save Changes when done.
- Open the Settings app on your device
- Tap Mail, Contacts, Calendars
- Tap Add Account…
- Tap Gmail
- Enter your account information, being sure to use your full Google Apps email address
- Tap Next
- Tap Save
You can now add additional accounts by repeating the same steps above.