We’ve identified one of the issues with Firefox which will be fixed when Firefox updates to version 57.
One of our users has also posted a solution for Firefox that seems to work that you can try in the interim:
1) Type “about:config” in the address bar.
2) Click the “I accept the risk” button.
3) Type “accessibility.blockautorefresh” in the search box (though, you might not have to do this – for me it is the third item from the very top in config).
4) Double-click on the first item that appears to modify the value to “true”.
5) Restart Firefox.
We are also working on improving reliability and performance while scrolling that will help alleviate this issue on other browsers like Chrome, Edge, and IE. Those changes should be available soon and we will update this thread once those have been released.
Thank you for your patience and understanding.
Thank you for your feedback.
We are investigating different ways to make accessing older emails easier for our users. We will report back when we have an update to this. Thank you for your patience!