Scaling qmail

[Alex Kramarov]

Hello.   I have to provide a solution to a series of mail servers (geographically distributed), serving from 20000 to 100000 users. Every server will support 1 primary (virtual) domain, and probably several small ones. I believe that vpopmail+mysql or qmail-ldap can provide a viable solution, but I didn't find any benchmarks, comparisons or recommendations to what solution can I use according to my load, and I also would like to know from you expirience, interesting, is there a machine that can handle 100000 users (whether Intel or Sun based) alone, or I need to use clustering.   Any input will be apriciated.   Alex.   P.S. I am surprised to see the lack of such info on qmail.org, maybe I will compile a page from the responces I get (if I get them).