Deepak,
You are asking stupid questions - this is looking very much along the
lines of someone wanting their homework done for them.
You are asking about disk space, but not saying whether that is queue
space, temporary working space, os install space or user storage - the
answers for each of those may be very different.
If you seriously want to build a system similar to, and scaling like,
gmail, then you are asking very much the wrong questions, and frankly do
not appear competent to know what the salient questions are. Frankly the
MTA is likely to be a very minor choice in the whole system.
As to which MTA is best out of sendmail or exim, the answer is obvious -
its one of Exchange, Qmail or Postfix, for appropriate definitions of
"best".
Nigel.
--
[ Nigel Metheringham Nigel.Metheringham@??? ]
[ - Comments in this message are my own and not ITO opinion/policy - ]
