Postfix/Message_with_300,000+_recips_via_alias_maps
From http://archives.neohapsis.com/archives/postfix/2009-06/0486.html
I asked for clarification on exactly why the owner-alias is needed, and how it works.
See here for discussion of docs on the matter: Postfix/Documentation_for_owner-*_companion_aliases
Barney Desmond:
> 2009/6/13 Wietse Venema <wietseporcupine.org>:
> > One final input: be sure to give each alias an owner-alias so that
> > Postfix will store the result of alias expansion in new queue
> > files.
> >
> > Otherwise, the result of expansion will not be stored. After failure
> > of delivery to one local recipient in the expansion, the whole
> > alias will be expanded again when delivery is retried, which is
> > something that the other recipients will not appreciate.
With the equivalent of:
/etc/aliases:
joe: :include:/home/majordomo/joelist
owner-joe: someone-who-maintains-the-list
The Postfix local delivery daemon will expand the alias joe and
store the result in a new queue file. This is triggered by the
existence of the owner-joe alias. That alias should always exist
with real mailing lists.
When the result of local alias expansion is not stored in a new
queue file, the same local delivery daemon that expands the alias
will also attempt to deliver mail to local recipients in the alias
expansion.
If any of those local local recipients needs to be deferred the
whole alias will be expanded again when delivery is retried.
It would be nice if Postfix could always store the result of
alias expansion into a new queue file, but unfortunately this
causes mail delivery loops when an alias appears in its own
expansion:
/etc/aliases:
root: root, foo, bar
At least with some Sendmail versions this will not loop and deliver
mail to root, foo, and bar.
The code that does this is incredibly complicated, so I haven't
tried to make it smarter and eliminate the need for humans to
specify owner-whatever aliases to help Postfix.
> Could you clarify what you mean by this? I get tables and the general
> architecture just fine, but I don't understand what you mean by an
> owner-alias. I'm assuming a trivial lookup of key=mylistexample.com,
> with 300,000 "values", presumably all external email addresses.
> Or perhaps I'm misinterpreting this, given that you're referring to
> local recipients. I'm not sure why re-evaluating the alias would cause
> multiple delivery (that's what the other recipients won't appreciate,
> right?)