Re: qmail vs sendmail

Zhenying Gu <[email protected]> wrote:
>
> I can find the comparison between qmail and sendmail on books published many
> years ago [...] I am sure that some of the issues with sendmail have been
> fixed.  I would like to get the comparision between latest version (or close
> to the latest version) of sendmail to qmail.

I'm sure you can get the comparison from a sendmail point of view elsewhere,
so I'll just provide my own opinion, which may or may not be shared by others
in the qmail community.

Things that get "fixed" in sendmail -- things like adding features, fixing
security bugs, performance problems, and other errata -- don't really change
the comparison between sendmail and qmail.  That's because sendmail's major
problems aren't just code-quality issues; they're problems with the *design*
of sendmail.

sendmail is still a huge, monolithic, labyrinthine set-uid binary with an
absolute mountain of accumulated technical debt, and it will always be so, no
matter how many "fixes" you apply to it.  If it were to stop being these
things, it would no longer be recognizably sendmail.

qmail's advantages (it does have disadvantages as well) stem primarily from
its superior design.  It is a set of small, tightly-defined, securely-coded,
cooperating processes, all of which distrust each other and require absolutely
minimal priveleges to do their jobs, and which communicate with each other in
very simple, predictable, verifiable ways.

qmail itself hasn't changed much in a very long time.  But that's (mostly)
okay; people keep adding new capabilities to qmail systems by plugging in
their own extensions and addons -- which is possible thanks to qmail's modular
design.

Charles
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