On Wed, Dec 23, 2009 at 10:13:28PM +0100, Christoph Anton Mitterer wrote:
> Quoting Wietse Venema <wie...@porcupine.org>:
> >>> Virtual alias maps apply to all domains.
> >>Uhm... ok,.. but for what is virtual_alias_domains then good for?
> >See: http://www.postfix.org/ADDRESS_CLASS_README.html
> I've had read this before,.. but still did not understand the need
> for virtual_alias_domains.
You can choose to have a domain (for which you are the MX host) in
which ALL addresses are aliased to other (valid, local(8) or remote
or virtual(8)) addresses.
A common use case for this is when using local(8) delivery, but
desiring to have namespace separation. If your user Alice should get
mail for al...@example.com but not for al...@example.net, you cannot
list both example.com and example.net in mydestination. But you can
have example.com in mydestination and example.net in
virtual_alias_domains.
> Now I think I might:
> - virtual aliasing always takes place, as you said before
> - the envelope recipient address might be rewritten to any address
> - if the resulting address has a domain part which is already a
> local, relay or virtual mailbox domain it should be accepted
> - but if not, and the mail goes to some remote domain, the mail
> would be rejected (unless the MTA is an open relay)
> => Therefore one has to "whitelist" the virtual alias domain...
>
> Does this make sense?
Um, no, not to me, you lost me at "would be rejected" ... that is
possible of course, but why in particular do you think so? Yes, it
could and might fail SPF checking.
Also, "whitelist" is not right. A virtual alias domain is your
domain. To outside clients there is no difference between that and
any other class. You accept mail for valid recipients, reject for
others.
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