Ditto will support the email clients: Mail (iPhone), Gmail and Outlook.
From the Ditto app home screen, tap "Custom Vibrations," and then tap "Emails." Make sure this switch is toggled on such that it appears green.
You'll want to make sure you have your phone set such that you receive e-mail notifications as well. Below are instructions on how to ensure this (please note that some Android phone instructions will vary from model to model).
Go to "Settings" > "Notifications".
From there, tap on your email app of choice. Select either "Banner" or "Alert" notifications.
Go to "Settings" > "Sounds and Notifications" > "Application notifications"
From there, tap on your email app of choice. From there, you can establish which email account notifications you would like to receive.