Follow these instructions to leave a copy of your mail on the server using these mobile devices:
iPhone®, iPad®, and iPod®
1. On the Home screen, open the Settings app.
2. Select “Passwords & Accounts”.
3. Tap the account you want to edit.
4. Tap “Advanced”.
5. Under “Incoming Settings” change “Delete from server” to never.
Due to the different versions of the Android device and the many mail clients that can be used on those devices, the following is an example of just one of those clients.
Please contact your provider if you need assistance in finding the location of this advanced setting.
1. Access your mail application, then tap the Menu or More Settings option.
2. On the Settings panel, tap the Account settings.
3. Tap Incoming Settings.
4. Find and update the Delete Email from Server setting.
Your mail now leaves a copy of the message on the server.