I will admit that I find configuring mail servers the biggest PITA I have come across but eventually you can get it all in place. I find the biggest headache is these self-righteous email spam groups that instead of black listing a single IP that is sending out spam they will blacklist the whole freaking range. There is no oversight to these sites like spamhaus; they block as they see fit. They even block the big players like 1and1.com. I have never sent out a single piece of spam in my life but I have to deal with these XXXXX way too often.