Gmail - Attachment icon and reading pane by Chris Menard
У вашего броузера проблема в совместимости с HTML5
UPDATE July 2018: Gmail had a makeover and the Preview pane is available by going to Settings - Advanced - Enable preview pane - save. Here is a screenshot of how it looks.
https://drive.google.com/file/d/1IayXy383owLIpjwToDhLdXtvf0CIgpaq/view?usp=sharing
You can show in Gmail an attachment icon instead of the paperclip. For it to work, you need to use Chrome.
Another trick is to turn on the reading pane in Gmail. It can be either at the right or below.
www.chrismenardtraining.com