Why does Zoho use Adobe Flash in the Mail application?

Why does Zoho use Adobe Flash in the Mail application?

On 2 different computers I tend to have this problem.  I'll open my browser and every time I click on an email, or a label, or a folder - I'll get an error message from Adobe Flash notifying me that the application has crashed.

I generally just have to restart the browser and the message will eventually go away.  Sometimes I've had to go as far as uninstalling and reinstalling flash, and restarting my browser to make the error message cease.

My question is - why is flash used in the first place? I'm not an expert web developer, but I can't seem to actually find the flash element on the page.  What is it being used for that all the HTML/AJAX-y can't do on it's own? 

And is there a way I can opt out of whatever features Flash is providing?