I enabled EXPN and VRFY (Any reason not to keep this enabled?), and when I try to EXPN the address in question, it fails. There is no data in LDAP for domain2.com, only domain1.com. domain2.com is only referenced in hosteddomains, and esmtpacceptmailfor.dir. makehosteddomains, makeacceptmailfor have been run, and a 'strings' of the dat files showes the domains were added.

What am I missing?

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Well, the only thing I can tell you right now is that this particular error is ok. Alias lookups occur before hosteddomains is checked. courierldapaliasd does not check hosteddomains.

The other useful thing you could do is make sure EXPN/VRFY is enabled, and poke around on port 25. EXPN will, essentially, tellsyou what alias expansion does. On my server, for example:

EXPN post...@courier-mta.com 250 <sa...@mail.courier-mta.com>

On the other hand,

EXPN mrs...@courier-mta.org 500 <mrs...@courier-mta.org> not found.

That's because this address is not an alias, but an actual mailbox.

VRFY checks deliverability after alias expansion:

VRFY mrs...@courier-mta.org 250 <mrs...@courier-mta.org>

VRFY post...@courier-mta.com 550 User unknown.

That's because this address is not an actual mailbox, but an alias. On the other hand:

VRFY sa...@mail.courier-mta.com 250 <sa...@mail.courier-mta.com>