On 12/03/18 07:12, jlftl wrote:
> Wietse Venema wrote
>> jlftl:
>>> Thank you very much for the responses!
>>> This is a small, personal setup with low traffic so I will definitely
>>> explore using notify_classes to try to get more feedback on the failures.
>>> Remote server legitmacy - *.dbsintl.net appears to be a third party
>>> hosting
>>> solution for small businesses.  In the example provided before, I can
>>> correlate the timestamps in my mail.log to attempts to generate e-mails
>>> from
>>> a particular website to myself (e.g. updating my e-mail address, etc.).
>>> Coupled with the failure to receive mail from nabble, I have to assume
>>> the
>>> problem is on my end.
>>> Here's the output from postconf -n (with my server/domain names
>>> redacted):
>> If this is the server that logs 
>>     unknown[] ehlo=1 mail=0/1 quit=1 commands=2/3
>> but no logging about rejected commands, then there is no Postfix
>> setting that would change the result.
>> To see the client's MAIL FROM command you can turn on verbose logging
>> with
>>     postconf debug_peer_list=
>> or use tcpdump as described in http://www.postfix.org/DEBUG_README.html.
>>      Wietse
> I've finally had time to circle back to this and was able to reproduce the
> problem receiving mail from nabble (for the postfix users forum) with
> notify_classes enabled.  I don't know if this particular issue is my only
> problem, but for the time being it's the only one I've had to opportunity to
> reproduce.  Here is the result from the postfix forum registration e-mail
> (my server/domain redacted):
> Transcript of session follows.
>  Out: 220 <myserver>.<mydomain>.net ESMTP
>  In:  ehlo hello
>  Out: 250-<myserver>.mydomain>.net
>  Out: 250-PIPELINING
>  Out: 250-SIZE 104857600
>  Out: 250-ETRN
>  Out: 250-STARTTLS
>  Out: 250-8BITMIME
>  Out: 250 DSN
>  In:  help
>  Out: 502 5.5.2 Error: command not recognized
>  In:
>  Out: 500 5.5.2 Error: bad syntax
> My installation does not appear to recognize the extended smtp "help"
> command.  I've attempted to do some research on this but "help" is an
> awfully generic string to search for, so other than determining that it is a
> valid estmp command I'm not sure what I need to do to correct it.
> Thanks!
> --
> Sent from: http://postfix.1071664.n5.nabble.com/Postfix-Users-f2.html


do you have any evidence that this came from Nabble? If not I would not
overly worry about not accepting email from a client that sends the help
command to your server.

Implementation of the help command is not needed for successful email
transmission. It's not part of the minimum set of commands needed for an
smtp server.  Given that the smtp protocol is generally used between two
programs and not by someone typing in the commands, there is very little
use for implementing the help command in the smtp server. It is not
supported by postfix.


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