January 27, 2020 11:49 AM, "Tassilo Philipp" <tphil...@potion-studios.com> 
wrote:

> Hello,
> 
> I noticed that for most emails I submit through my instance of OpenSMTP, 
> there are most of the time
> (but interestingly not always) two envelopes in the queue. However, mail 
> delivery works fine, and
> only one copy arrives at the recipient.
> 
> [...]
> 
> Looks like they are exact duplicates, but with their distinct envelope IDs. 
> Here's the relay log:
> 
> Jan 27 10:20:43 schacht01 smtpd[50381]: 11490b9d19a2b420 mta delivery 
> evpid=10da45aca8ae47a5
> from=<sen...@snd.com> to=<recei...@rcv.com> rcpt=<-> 
> source="<mail_server_addr>"
> relay="<recv_mx_addr>" delay=8s result="Ok" stat="250 2.6.0 
> <2020015810049931962...@snd.com>
> [InternalId=3259974] Queued mail for delivery"
> Jan 27 10:20:43 schacht01 smtpd[50381]: 11490b9d19a2b420 mta delivery 
> evpid=10da45acc22f61bd
> from=<sen...@snd.com> to=<recei...@rcv.com> rcpt=<-> 
> source="<mail_server_addr>"
> relay="<recv_mx_addr>" delay=8s result="Ok" stat="250 2.6.0 
> <2020015810049931962...@snd.com>
> [InternalId=3259974] Queued mail for delivery"
> 
> So, both are relayed, it seems, however, on the receiving side only one copy 
> arrives, and no errors
> reported. I guess that if there is a double relay, the receiver might still 
> only accept one copy,
> b/c the Message-Id being the same? Or isn't there a double relay to begin 
> with?
> 

Both were relayed, the recipient probably deduped on the Message-Id



> I'm also a bit puzzled why in rare cases, only one envelope is in the queue - 
> what I would expect -
> but I cannot find why or what the difference is.
> 
> I have only one thing listening on the submission port:
> 
> # netstat -4an | grep -F .587
> tcp4 0 0 <mail_server_addr>.587 *.* LISTEN
> 
> The corresponding smtp.conf's config file line is, as well as the used 
> action/match pair:
> 
> listen on $listen_ext port submission tls-require pki mx_pki auth hostname 
> $mx_domain senders
> <sender_map> mask-src tag "MSA"
> 
> action "relay" relay helo $mx_domain
> match auth from any for any action "relay"
> 
> So I guess my question is very simple in nature: Is this normal behaviour, or 
> is there something
> going on that needs to be investigated?
> 

There is something that needs to be investigated, this is not normal no.

I won't rule out a bug in OpenSMTPD but given how envelopes are created, it is 
very unlikely:

a- an envelope is created for each RCPT TO in a transaction...
b- ... and additional envelopes may be created by aliases _during_ that RCPT TO

You provided only a partial smtpd.conf so it's hard to know if b- is possible 
here,
as relaying doesn't go through aliasing which would hint at a- being the 
explanation.
smtpd.conf has to be read as a whole otherwise troubleshooting is not possible.

You can run smtpd with `-T smtp` to inspect SMTP transactions as they are 
submitted,
you can also use `-T rules` to check which rule was matched and make sure it is 
that
match auth and not another one that got hit first.

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