Which RedHat disto works best with GreyList?

I am wanting to put a LINUX Sendmail box in front of my real (non LINUX) 
mail server and have it greylist and pass on (via SMTP) to the real server.  
I have other LINUX boxes here (web servers and DNS servers).

I have been working off and on (mostly off) to get a newer SendMail, 
threaded Perl, MySQL, etc on an older RH box.

Now that I am back on this project more full time, it looks like a mess :-)  
I got sendmail compiled but get strange errors, etc. I am thinking of wiping 
the system and just starting over.

Which RH distribution is new enough for me to avoid all the 
patching/updating/debugging - if any?  I assume it will have to be 
pre-Fedora.  If not RH, then another LINUX?  I usually use an older RH 
because I know it and can spend all my time on what I need to do and not 
re-learning the OS.

Thanks,
Dennis