You can try this:

*) Add one more account under domain, e.g. catchall@ (just an example, it can be any address)
*) Set per-user relay for catchall@ to relay to your other mail servers. e.g. smtp:[xxx.xxx.xxx.xxx]:25
*) Set per-domain catch-all account to this newly created account "catchall@".

This way, Postfix still verifies existing accounts, and emails sent to non-existing address will be relayed to another server.

I think, from a functional point of view, there is a difference between the options:

* Mark as backup MX
* Relay without verifying local recipients

The first option should forward everything without any local activity, this is what BackupMX means. The second option is useless, since if you define a relay, but it's NOT a backupMX, it implies you want local recipient verifying, and only relay if verification fails.

However currently both set the backupMX flag, so do exactly the same.

That doesn't make any difference. Same error.

When BackupMX=0 and relay transport != 'dovevot', it should relay the incoming message using th defined domain transport if no local recipient exists.

When BackupMX=0 and relay transport is empty or set to 'dovecot', it should return "Recipient address rejected: User unknown in virtual mailbox table" if no local recipient exists.

I've been looking at the different cf files, and from a logical point of view I think relay_domains should be changed so it only returns the transport if no local mailbox exists, but I don't think you've got access to %u and %d in that query?

Maybe it will work this way:

* Add addition sql/ldap/hash file query AFTER domain transport lookup setting, e.g.

transport_maps =
    proxy:mysql:/etc/postfix/mysql/transport_maps_user.cf,
    proxy:mysql:/etc/postfix/mysql/transport_maps_domain.cf,
    proxy:mysql:/etc/postfix/mysql/transport_non_exist_accounts.cf    # <- Add this one

Since transport_maps_user.cf and transport_maps_domain.cf return transport for valid users/domains, transport_non_exist_accounts.cf should return transport setting for all non-existing accounts. You can write a proper SQL command in this file to return the relay setting of secondary mail server.

e.g.

5th post in this thread says adding 'backupmx=0' in transport_maps_domain.cf.

I added some debugging to the qmgr, and that confirms that the message is bounced higher up in the process, before it gets to the qmgr and transports are checked.

Well, I did exactly what you said. Let me recap:

main.cf contains:

transport_maps = proxy:mysql:/etc/postfix/mysql/transport_maps_user.cf, 
      proxy:mysql:/etc/postfix/mysql/transport_maps_domain.cf, 
      proxy:mysql:/etc/postfix/mysql/transport_maps_forwards.cf

transport_maps_user.cf:

SELECT mailbox.transport FROM mailbox,domain 
     WHERE mailbox.username='%s' AND mailbox.domain='%d' AND mailbox.domain=domain.domain 
     AND mailbox.transport<>'' AND mailbox.active=1 AND mailbox.enabledeliver=1
     AND domain.backupmx=0 AND domain.active=1

transport_maps_domain.cf:

SELECT transport FROM domain WHERE domain='%s' AND active=1 AND backupmx=0

transport_maps_forwards.cf:

SELECT transport FROM domain 
     WHERE domain='%s' AND active=1
     AND (transport LIKE "smtp:%%" OR transport LIKE "relay:%%")

Unless I've understood you completely wrong, this was you advice, yes?

With this config as soon as I set BackupMX to 0 on my test domain, the local mailbox starts accepting mail, and when there is no local mailbox, I get "Recipient address rejected: User unknown in virtual mailbox table;" as I explained.

*) '%s' should be '%d' in transport_maps_forwards.cf
*) Please verify transport_maps_forwards.cf with below command first:

# cd /etc/postfix/mysql/
# postmap -q 'non-exist-user@your_domain.com' mysql:./transport_maps_user.cf
# postmap -q 'your_domain.com' mysql:./transport_maps_domain.cf
# postmap -q 'your_domain.com' mysql:./transport_maps_forwards.cf

With these corrections there are no differences though.

Still, with the transport mentioned in the previous post defined on "my-domain.com", and "backupmx" set to 0, any email that comes in for "exist-user@my-domain.com" is correctly delivered, and email for "non-exist-user@my-domain.com" is bounced, and not forwarded:

Delivery to the following recipient failed permanently:

    non-exist-user@my-domain.com

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the server for the recipient domain my-domain.com by iredmail.my-domain.com. [x.x.x.x].

The error that the other server returned was:
550 5.1.1 <non-exist-user@my-domain.com>: Recipient address rejected: User unknown in virtual mailbox table


----- Original message -----

DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=20120113;
        h=mime-version:date:message-id:subject:from:to:content-type;
        bh=WYqNRWWXIehP4s5147vSFraNlCfTqrvduNQ7U4iCxxw=;
        b=tfoV4WNsu3+NhjXyJTHbJtXGTzt4FRqcCUprFd0N/cBqSL4vWQH3V17GdcjbCLmPaj
         iuktkdgRkVPZpAW06BxmZihdTUeHnf/wM5yZDXr/azIzht6hMkwQYZevhEqr23bVqa4h
         HMf1yVgNaQE4ixwbig61JQUvr0nSBLkW2+widD1SFoJu/ufWYuF/Z/CAMH3IKzWke2l2
         jt4HJIOw8uO/vHcsS0OEKkmWvM/6/LMr3FXJcfcTU/3RZCu4tY84tV/IuP5igLkVCzeM
         oV+14M4VBCmBZtQiugJzd57WrRDKUwcnT6+j1fSU4MdMhWiWjs6iofLsxANjf9uxSI0e
         9jAA==
MIME-Version: 1.0
X-Received: by 10.180.96.41 with SMTP id dp9mr13379877wib.13.1417611733057;
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Date: Wed, 3 Dec 2014 14:02:13 +0100
Message-ID: <CAMK7jNa7dxWDHikrHMRdA0fuFjHC6GSqW_2_xm=GsH7_HkbUFg@mail.gmail.com>
Subject: still ok?
From: Harro Verton <my-private-account@gmail.com>
To: non-exist-user@my-domain.com
Content-Type: multipart/alternative; boundary=f46d043bdc58c747ee05094f7310

I'd rather you responded with a solution to the problem instead of with a joke, because we're still no inch further in solving this.

I already replied that even with my correction to your suggestion, it doesn't work. The "postmap -q" query returns the correct information, but it still either forwards, or delivers locally, but not both. So the process doesn't even get that far.

Hi,
I'm trying the same thing as TO with no success. I really would appreciate an idea how to make postfix accept a non-existing address and trigger the relay process. Should I open a new thread or continue here?
Thank you
Lucas

Hi @luvo, @harro.verton,

Could you try this?
https://gist.github.com/iredmail/fda90a … c18638e047