Using the Apple Mail app on iPhones and iPads to send pictures to Postie results in only the pictures showing up with the text missing. This is because by default the mail app does not send a html version of the email, only plain text.
Starting in version 1.8 Postie now has the option to "fall back" to the other "Preferred Text Type" just change the value to "Yes" click Save and you are good to go.