IPhone pictures get rotated when posted

[sigh] This problem seems to have gone on for ages and pops up many different ways. I tested postie from my iphone, selecting a portrait picture and sent in an email. When the post was published, the featured image had rotated 90 degrees. It was always in portrait on the iphone, but now its turned into landscape the wrong way up.[/sigh]

What is the solution here? Thank-you.

https://wordpress.org/plugins/postie/