Why some say "rpm hell"

[AP]

On Thu, Nov 28, 2013 at 12:23 AM, David <dgboles at gmail.com> wrote:

> Frankly I find it hard to comprehend just how the browser and any of
> it's settings, would have any interaction with an email written on the
> Gmail Web interface, or any email interface.

I wonder to think this but I never earlier noted all this aspects.
What and why would a browser would do anything with the users'
personal email settings...?