[CentOS] the Postfix packages are way too old

If you deliver more than a few emails to the outside world, especially 
if a good portion of those go to Yahoo, you may want to read this message:

http://marc.info/?l=postfix-users&m=127689518629249&w=2

Actually, read the whole thread, it's interesting and the discussion 
still continues:

http://marc.info/?t=127619611600001&r=1&w=2

TLDR: The 2.3.3 Postfix version that comes with RH / CentOS 5 doesn't do 
delivery rate control very well and has a habit of annoying some email 
providers. A simple upgrade from 2.3.3 to 2.7.0, no config changes, can 
improve delivery rate by 50% in some cases (e.g. if you deliver 
thousands of emails to Yahoo). With config changes, the improvement 
might be even bigger.

Fun fact: Postfix-2.3.3 has been released in August 2006. Think about that.

-- 
Florin Andrei
http://florin.myip.org/