Recently I received some complaints of users no longer being able to reply to email messages on their samsung smartphone because the email client gets stuck on “loading messages” after clicking the reply button.
This issue seems to be caused by an update of the android system web-viewer application which is present on all google play enabled android phones. The quickest way to solve this issue is to disable the web-viewer, which causes it to roll-back all updates.
You can do so by navigating to settings>applications, here you look for the system-app Android system WebView and click on disable.
After restarting the phone the email client should work as expected again and you should be able to reply to any message you want.
I have seen this issue occur on a wide variety of samsung android phones including the galaxy xcover 3, samsung galaxy s5, galaxy s6, and galxy s7