I usually use an image hosting site to post but out of curiosity I tried using the attach option and it worked fine.
Just out of curiosity was the photo originally shot horizontally and then rotated on your phone with an image viewer?
I downloaded your photo and rotated (also fixed the exposure
) using image editing software on my phone and it worked. My guess is that however it is being rotated (assuming it's on your phone) is just telling your device to show it vertically and not actually changing the orientation of the photo.