The other day, I went to print an email, from my iPad Air 2 to my non 'Air Print' compatible HP printer, however, there was no 'Open With' icon, within the Mail app since updating to iOS 10.
Previously, what would happen is this : I have a Printer Pro app on my iPad Air 2. When I wanted to print an email, at the top right of the Mail app, there would be an icon which, when tapped, would give you the option to open the email, within another app - so in this case, I would find the email I wanted to print and tap the 'Open With' icon, and one of the options would be the Printer Pro app, however, now in iOS 10, this 'Open With' option seems to have been removed??

Previously, what would happen is this : I have a Printer Pro app on my iPad Air 2. When I wanted to print an email, at the top right of the Mail app, there would be an icon which, when tapped, would give you the option to open the email, within another app - so in this case, I would find the email I wanted to print and tap the 'Open With' icon, and one of the options would be the Printer Pro app, however, now in iOS 10, this 'Open With' option seems to have been removed??