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Subject: Re: Sendmail --> PostFix conversion
From: Brad Knowles (blkskynet.be)
Date: Tue Sep 19 2000 - 14:26:45 CDT

At 11:34 AM -0700 2000/9/19, Harry wrote:

> Notice how I did not use the term 'identical' anywhere in my message, for
> good reason. I did take aim at the term 'drop-in replacement' that is used
> in regards to Postfix.

        I'm looking at <http://www.postfix.org/>, and I'm not seeing this term.

        From <http://www.postfix.org/motivation.html>, I see:

                Postfix is my attempt to provide an alternative to the
                widely-used Sendmail program. Postfix attempts to be fast,
                easy to administer, and hopefully secure, while at the
                same time being sendmail compatible enough to not upset
                your users.

        From <http://www.postfix.org/goals.html>, I see:

                * Compatibility. Postfix is designed to be
                sendmail-compatible to make migration easy. Postfix
                supports /var[/spool]/mail, /etc/aliases, NIS, and
                ~/.forward files. However, Postfix also attempts to
                be easy to administer, and therefore it does not use
                sendmail.cf.

        From <http://www.postfix.org/architecture.html>, in addition to a
lot of stuff that talks about how postfix is different from sendmail,
I see:

                Postfix is intended to be a Sendmail replacement. For
                this reason it tries to be compatible with existing
                infrastructure. However, many parts of the Postfix
                system, such as the local delivery program, are
                easily replaced by editing an inetd-like configuration
                file. For example, the plan is to provide an alternate
                local delivery program that runs at a fixed low
                privilege, for POP/IMAP users that never log into the
                shell, and that may not even have a UNIX account.

        Looking at <http://www.postfix.org/faq.html>, I don't find the
term "drop-in" anywhere on the page. In fact, I went so far as to
set up a complete mirror of the entire postfix web site, just so that
I could grep through all the available pages for the term "drop-in".
I didn't find it anywhere.

        In short, I don't know where you got this idea that postfix was a
100% complete perfect drop-in replacement for sendmail (including
using all the same configuration files and configuration file
formats, etc...), but I certainly can't see anything that should lead
you to this conclusion from any of the documentation I can find.

> In view of the term drop-in replacement, I do expect a third-part
> aftermarket part to work as effectively as a Ford part when I place them in
> my engine. The same holds true for thrid-party ink-cartridges, vs. hp print
> cartridges.

        I would like to see where you get this term "drop-in" from. I
can't find it in any of the postfix documentation that I have looked
at.

> While I understand the inherent problem with the syntax and decoding of
> sendmail.cf files, there are plenty of other files (like the virtusertable,
> etc..) that could just be used as is, yet still need some massaging.

        The places where postfix is different from sendmail usually stem
from philosophical differences between the authors of the respective
programs, or from architectural differences in how the programs have
been implemented. Wietse generally does actually pay some attention
to actively making postfix as sendmail-compatible as feasible, but
there is obviously only so much he can do.

> A friend of mine, as well as myself have wanted to use
> Postfix as a replacement to our Sendmail installations, but have shied away
> from it so far, precisely because of the conversion issues, and not wanting
> to cause any downtime for our systems.

        The key thing that is so cool about postfix is that it is
generally useful right out-of-the-box. You don't have to make any
configuration changes (or hardly any) to get it to work reasonably
well.

        Just like sendmail, you can always set up postfix to listen to a
different port (or IP address), so that you can have them both
running in parallel, and you can test out various options and ideas,
until you're satisfied that you have built a server that is
sufficiently close to the old one in terms of the operations it does
and the features it has, and then you can cut it over to be your
primary mail service, while you continue to keep sendmail running as
the backup.

> Cute, arrogant and elitist statement - and super-helpful for newbies that
> are looking to get started with Postfix.

        You are free to interpret that statement however you like.

        Regardless, some level of reality has to be injected into the
situation, and you should consider yourself lucky that I was in a
good mood today, and decided to be as humorous as I could when doing
so. 

--
   These are my opinions -- not to be taken as official Skynet policy
======================================================================
Brad Knowles, <blkskynet.be>                || Belgacom Skynet SA/NV
Systems Architect, Mail/News/FTP/Proxy Admin || Rue Colonel Bourg, 124
Phone/Fax: +32-2-706.13.11/12.49             || B-1140 Brussels
http://www.skynet.be                         || Belgium

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