[CentOS-docs] Short postgrey guide?

[Karanbir Singh]

Ned Slider wrote:
>> Could we add the following image:
>> http://wiki.centos.org/HowTos/postgrey?action=AttachFile&do=get&target=postgrey-en.png 
> Thanks Alain - nice image and explains the concept well.
> 
> Any objections to adding it from anyone?


Please go ahead and add it. It looks clear enough to me.

btw, I just decimated your article with loads of other info that people 
might find interesting. All of that came from my head, so if someone can 
technically proof read it once would be appreciated.

- KB