On 29 Sep 2019, at 12:37, Ramon F Herrera wrote:
I am vaguely familiar with Postfix. I am told that is as capable as
ole' sendmail, and much easier to manage.
Any suggestions, tips about that upgrade are most welcome.
As someone who has worked with Sendmail from the dawn of v8 and with
Postfix since v2.4, I must confess that on a standalone basis, in
theory, Sendmail has greater flexibility and can, as a matter of
provable computer science, do things Postfix cannot. However, the
overwhelming bulk of the functional space where Sendmail stands alone
would normally be things no one really wants to do or should do. That is
the product and the price of using a NP-complete programming language
for sendmail.cf. As a practical matter, the fact that Postfix has a
robust set of interfaces for external tools (including Milter software)
means that there's no real difference in capabilities. When I have a
choice, I use Postfix.
The first thing to understand about Postfix is that Postfix is not one
program, it is a suite of closely interdependent programs that handle
distinct aspects of the mail acceptance and delivery process. Its
components and configuration parameters are meticulously documented with
man pages and a collection of about a dozen "readme" files. There's no
ultra-compact programming language composed almost entirely of
punctuation that nothing else in the world uses, so your skill of
hand-editing sendmail.cf will not help you with Postfix. There is an
extremely helpful, well-focused, and civil Postfix Users mailing list
where the primary author, the most active contributor to the code, and
the authors of the two comprehensive books on Postfix are active.
In doing the upgrade, you should start by making sure that you have a
solid understanding of what your Sendmail configuration is. For most
people, that is well-defined in a sendmail.mc that they use to build
sendmail.cf, but since you've written about direct sendmail.cf
modification, you may have a bit more work nailing down what exactly
you're doing with Sendmail so that you can find the Postfix analogs.
Beyond translating configuration, there's one important part of Postfix
that has no Sendmail equivalent: the postscreen front-line SMTP screener
program. Postscreen implements a greeting pause, weighted parallel DNSBL
checking, and optionally a few other spambot-detection tactics. Because
it is a unique tool, some distributions do not enable it by default.
Make sure you have it set up, because it is an extremely effective and
lightweight tool.
--
Bill Cole
b...@scconsult.com or billc...@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
