Mail server implementation of gmail,yahoo etc...
 

hi,

Any one got an idea of how big players like gmail,yahoo etc implement their mail server, I mean to ask the details of the
1) Various Mail server software these guys use[MTA].
2) Details of hardware implementation[server farm details if any..].
3) What operating systems they use?
4) If they use linux then, Does they use any directory services[LDAP] specific setting for mail server?

Kindly share the right information if any one knows or direct me to any page where I could get more information on implementing mail servers on big iron computing.

Thanks in advance.