>> but everything is developing so fast that news is out dated after a few months
qmail remains the best and most secure MTA (not even a vulnerability found so far since it was first released till now). In fact, all of Dan Bernstein's software are highly secure and well-written for performance and reliability.
Yeah right, everyone is using Sendmail, BIND or so. So what? everyone is using it makes it popular, but not necessary the best in a security point of view. The majority of people don't care about security, even if they do care, they are too lazy to search for alternative. Say IE for example, why is it the dominant web browser? Not because it's secure (full of holes and not RFC complicance, in fact). It's the fact that there are not too many alternative and M$ still rule 95% of desktop. Despite the fact that I love *BSDs so much, I have been using win98SE continuously simply because I wanted to run as many software as possible available only on win32 platform. You now may wonder if I care about security. Yes, I implement all kind of encryption or SSL for all kind of TCP services as much as possible (just to name a few: apache, smtp, pop3, imap, ftp), plus a strict firewall policy. Too much bull**** here so now let's talk about why Dan's djbdns is the ideal DNS server as a replacement for BIND.
Yes, everyone runs BIND even though everyone knows it doesn't have a good security record. So what makes djbdns better? You first need to understand briefly about how DNS works. There are two major distinction here: 1) DNS caching; 2) DNS service
For DNS caching, you don't need to host any domain at all. It's cache-only and your server will cache (remember) the info it query so on future query, the cache data will be used in purpose for speed and resource. In BIND, it handles cache extremely poorly (9.x is slightly better).
For DNS service, this is so-called running a DNS server to be authoritative for particular domain. What makes djbdns better than BIND in this regard is speed, efficiently, security, performance, reliability and durability. It's time to quit here, if you are interested in djbdns and wonder why it's a replacement for BIND, check out ->
http://cr.yp.to/djbdns.html and take an hour or so and read up all the docs there. I bet you will replace your running BIND immediately with djbdns.
Go back to qmail, to maximize performance and reliability, you should be using Maildir mailbox format.