[linux-elitists] Postfix vs Exim
Thu Sep 19 20:55:44 PDT 2002
Ok, this isn't meant as an Exim rules Postfix sucks (or the other way
around), I think both MTAs are very good and I'm trying to see which one is
better for each case.
I know exim fairly well, but I don't know postfix well enough to make a fair
comparison, so this is targetted at the few who may know both fairly well
- I know about the security model difference between exim and postfix.
- I do not care much about which one is faster at what, they're both fast
enough as far as I'm concerned
- I know that because postfix isn't monolithic like exim, and that one of
the prices to pay is that it doesn't do deduping (i.e. if a message is
sent to you and an email alias, you get two copies). If postfix's secure
module approach has other drawbacks, I'm interested to hear them
- I have been told that postfix can do content filtering and bounce at SMTP
time (like exim4's ACLs) and after data (like exim's system_filter).
Confirmation would be appreciated
- I don't know if postfix can do fined grained ACLs like exim4 and do RBL
rejects but only if the from domain matches a string, the connecting host
is in a certain IP range, and none of the receipients is postmaster for
instance. Is postfix that configurable?
- I don't think postfix can do SMTP callbacks or callouts like exim.
- I'm not sure that postfix can do the equivalent of exim's local scan or
sendmail's milters. Confirmation appreciated
- postfix has an extensive lookup cache, which is a huge advantage over exim
if you are doing ldap lookups (ldap is slow, and exim will not cache the
lookup longer than the process runs)
- exim can lookup users to deliver for in ldap or nis by using getpwnam,
using the C library and nscd, but if it does so, it cannot distiguish a
non existant users from a connection refused.
As a result, you should not use getpwnam and libnss_* for any MTA, but
instead you should have the MTA behave as a NIS or ldap client and do the
This is possible, but a bit kludgy in exim, and if you do so, exim will
not be able to cache the result.
I've been told that postfix supports this better and will cache the result
of the nis/ldap queries as if you were using nscd
- Both MTAs support TLS
- Exim is the only MTA I know that can create virtual aliases on the fly
(i.e. mailman aliases)
- Can postfix, like exim, do mail routing depending on a file (i.e. run
procmail if there is a ~user/.procmailrc or run vacation if there is a
- Does postfix support complete header rewriting (on all the headers, per
header and with regular expressions), like exim does?
- What other cool things can postfix do that exim can't?
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems & security ....
.... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/ | Finger email@example.com for PGP key
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