Odgovor na tvoje pitanje je iz 2 dela.
1. deo nacices na :
http://cr.yp.to/surveys.html
http://qmail.drenik.net/blurb.html
http://cr.yp.to/qmail/users.html
2. deo je sledeci :
Big boys using Qmail MTA :
A number of large Internet sites are using qmail: Hotmail's outgoing mail (although Microsoft thinks they're going to transition to W2K), USA.net's outgoing email, Address.com, Rediffmail.com, Colonize.com, Yahoo! mail, Network Solutions, Verio, MessageLabs (searching 20M emails/week for malware), listserv.acsu.buffalo.edu (a big listserv hub, using qmail since 1996), Ohio State (biggest US University), onelist.com (which has merged with egroups, another big free mailing list service), Listbot, USWest.net (Western US ISP), RIPE, Matchlogic, Telenordia, gmx.de (German ISP), NetZero (free ISP), Critical Path (email outsourcing service w/ 15M mailboxes), PayPal/Confinity, Hypermart.net, Casema, Pair Networks, Topica, MyNet.com.tr, FSmail.net, and vuurwerk.nl. DrenikNet ;)