[pfx] Re: help debugging SASL authentication failure: No worthy mechs found

On 04.04.2026 23:37, Marvin Renich via Postfix-users wrote:
> * Greg Klanderman via Postfix-users <[email protected]> [260404 15:06]:
>> Hi Marvin,
>>
>> Thank you for your reply.. that matches what I see.
>>
>> I had not realized recommends were installed by default.. I was
>> wondering how those and suggests differed but hadn't gotten to looking
>> it up yet.
>>
>> I had not used --no-install-recommends, simply 'apt install postfix'
>> and libsasl2-modules was not installed.
> 
> [snip]
> 
>> The following day, it shows that I ran 'apt upgrade' and libsasl2-2
>> was upgraded, but not libsasl2-modules (which appears to have matching
>> versioning).
>>
>> I have to conclude that libsasl2-2 must have already been installed,
>> without libsasl2-modules, when I installed postfix.
>>
>> Does that make sense?  Since it was not installing libsasl2-2, the
>> recommends: libsasl2-modules was not considered, only the postfix
>> package suggests: libsasl2-modules.
> 
> Exactly.

Actually, when apt installs something new, it considers Recommends: for
*all* packages it installs.  So if A depends on B, and B recommends C,
and you install A, C will be installed too (unless you disable
installing recommends).  Ditto for the case when A *recommends* B, etc.

In short, by default apt installs Recommends for everything it installs.

This is why this problem hasn't been a problem for all these years.

And yes, this does not answer the question why the OP doesn't have
libsasl2-modules installed on the system.  I can't answer it either.

>> Maybe it would make sense for postfix to directly recommend: rather
>> than suggest: libsasl2-modules?
> 
> I don't think so, but I'm not sure.  The Debian maintainer would be the
> person to decide this.

It should not.  There are multiple possible sasl implementations (there's
also dovecot for example), and actually, there are a lot of installs
where nothing else besides basic mail system is needed - consider a
case of a server in a server room, which should collect mails from
cron and send it to a dedicated mailhub: such case is actually very
common.  So actually we have another problem, where an *extra*,
unwanted, software is installed by default.

Choosing defaults is not a fun problem, - you cant suit every needs
out there.  But I really like the way debian does here, allowing to
install a minimal system with just a bare minimum software for the
task at hand, instead of always insisting on everything being installed.

Thanks,

/mjt
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