[pfx] Re: Avoiding message doubling via virtual aliases

Wietse Venema via Postfix-users wrote in
 <[email protected]>:
 |Steffen Nurpmeso via Postfix-users:
 |>|Before mailing list expansion, both virtual_alias_maps expansion and
 |>|recipient deduplication happen while an inbound message is written
 |>|to a queue file.
 |>|
 |>|After mailing list expansion, both virtual_alias_maps expansion and
 |>|recipient deduplication happen while an outbound message is written
 |>|to a queue file. 
 |>|
 |>|By default, deduplication happens only for the first 1000 recipients
 |>|(duplicate_filter_limit = 1000). You can set the limit larger;
 |>|modern systems should handle 10x or 100x easily.
 |> 
 |> Ah, i have forgotten to add
 |> 
 |>   mydestination = $myhostname, localhost.$mydomain, localhost, lists.$myh\
 |>   ostname
 |> 
 |> Other than that i think i reread VIRTUAL_README from scratch.
 |> I do not understand otherwise, sorry.  (The initial message that
 |> triggered me was an inbound message.)
 |
 |I might add, in case that it isn't obvious from the above, that there
 |is no deduplication across multiple queue files.
 |
 |If the mailing list generates multiple submissions into Postfix,
 |then duplicates will be suppressed only within the same queue file.
 |
 |If you really want useful information from me, then I need to know
 |what route the duplcated recipients took in terms of queue files.

Well, please excuse me, i do not understand.  No, it is not
obvious.  I mean, i have shown the sendmail(1) invocation with two
recipients -- granted this is all local --, and the one is
expanded, so we effectively have the same address twice, and that
is then "delivered" via local, it is actually an alias that runs
a program, and that is run twice.
Whereas i would expect something like

  </dev/null s-nail -:/ -Sstealthmua -Smta=test \
    -X 'alias [email protected] [email protected]' \
    -s hi [email protected] [email protected]
  From steffen Wed May  6 22:45:29 2026
  Date: Wed, 06 May 2026 22:45:29 +0200
  To: [email protected]
  Subject: hi

 | Wietyse

Hand-written signature?  Oh!

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)
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