Viktor Dukhovni:
> On Tue, Apr 21, 2015 at 09:50:05PM +0200, josef radinger wrote:
>
> > a domain xy.org which has users on two servers: one exchange server (B)
> > and one postfix(A). in front of that two systems is another portal-host,
> > which cannot distinguish between mails for users on system A or on
> > system B and therefor send everything to A.
>
> What software does this portal host run? Does the portal host do
> any recipient validation, and if not why not?
>
> > users will get moved from exchange to postfix in batches
>
> Presumably (or ideally) Exchange has forwarding addresses configured
> for the users who are moving, and therefore should have a complete
> list of all valid users in LDAP.
>
> > and I would like to do the following:
> >
> > Postfix is the leading system and will receive all mails.
>
> Fine.
>
> > If a user is not already on postfix (and would generate a
> > "User unknown in virtual alias table") then the mail should be sent to
> > the exchange host.
>
> There is no need for "unknown" users, all users should be "known", and
> appropriate rewriting and/or transport rules will direct their mail to
> the right place.
>
> > I know this is not ideal, because of the possibility of backscatter.
>
> It is sloppy, and unnecessary. If the domain is a virtual alias domain,
> each user needs to be aliased to a real domain (u...@mailstore.example.com
> where u...@example.com is the original virtual address, and "mailstore"
> varies by user to route either to Exchange or local delivery).
This may not work when the exchange server expects u...@example.com
instead of u...@host.example.com. If we can't come up with a *simple*
solution for this, then we lose market share.
Wietse
