This has been resolved with the 5/3/16 release of Online Express.
Steps to Duplicate
1. Log into The Raiser's Edge 2. Select Online Express 3. Select Email Marketing 4. Choose Create a new email 5. Create an email and click on the style tab 6. Choose Selected Column style 7. Select the Footer section 8. Change the Horizontal alignment from center to left and back 9. Save & Continue 10. Send Email 11. Open on iphone with iOS 9 and see that the footer is misaligned