mail server

[Welty, Richard]

azeem ahmad writes:
> i have never configured it. i m a student not a sys admin. n i have to 
> configure a mail server that must meet enterprise requirements.
> its mine assignment. thats why i was asking about qmail and sendmail

from a performance point of view, any of the "big 4" Mail transports
can provide enterprise quality service. in fact, all 4 of them are used
in this manner in one place or another. high volume mail transport is
inevitably disk bound, cpu speed/count and choice of MTA are less important
than you might think.

sendmail is the ancestral MTA. it used to be a lot harder to configure
than it is now, but it's still no walk in the park. licensing is derived
from the BSD family of licenses.

exim is a spiritual decendant of smail (no common code though.) it's
monolithic in construction (which fans of qmail/postfix hate), but has
been pretty free of security advisories over the years. i have used it
for 10 years now, and don't feel any compelling reason to move on from it.
it works well. it is designed to be fairly easy to install in place
of a sendmail installation, although the configuration files are different.
licensing is GPL.

qmail is its own creature. it works hard at not being sendmail, makes a
number of unique decisions, and is heavily modularized for security purposes.
some of the unique decisions are controversial (e.g., massive parallel
delivery when only one destination host is involved.) licensing is most
assuredly _not_ open source.

postfix is modularized too, but maintains a useful degree of sendmail
compatibility. postfix users seem to like it a lot (i've never used or
learned it.) licensing is a complex ibm specific license that's sort of
open source. it'd be really nice if ibm would bag this license and put
postfix under the GPL or something.