> Yes, and thankfully these days it's fairly easy. If performance is an  
 > issue you might want to lean towards libspf2 rather than Mail::SPF  
 > (the reference implementation).  A full list of milters and other  
 > resources for setting up SPF (howtos etc) is here:
[...]

Thank you! 

I tried before on SL 4.5, but got lost trying to resolve failed
dependencies when installing the necessary packages. I'll give it
another try - now with SL 5.1.


Miguel A. Lerma