I came to post a similar question so I'll add it here.
First, I was very pleased to see how nicely post by email has come along. The last time I tried it, image attachments weren't even allowed! The Postie plugin seems to have stopped working so I was looking for an alternative.
Anyway, it worked just fine. But the picture that was posted was huge! When delivered by email it even gets cut off in size.
Is there a way of limiting the width and scaling down proportionately, like you can choose 600x600 with the WordPress app?
Thanks,
doug