bounced on alias name

[Thorsten Schnebeck]

Hi,

I use a kolab 2.2 master slave setup.
master server 1 lives in the internet and is imap host of domain A
slave server 2 lives in an intranet and is imap host of domain B
Kolab uses an LDAP mirror in a master slave setup.

There is user alpha. User alpha is a member of both domains. As in current 
Kolab you can not put one person to two email accounts user alpha uses one 
email address and an alias name:

mail: alpha at domain.a and alias: beta at domain.b

Everything works fine BUT I have here one side effect:
if I send a message as beta at domain.b to e.g. gamma at domain.b and 
kolabfilter has a problem (like exe-file as attachment) and wants to inform me, 
I see this:

 to=<beta at domain.b>, relay=kolabmailboxfilter, delay=0.16, 
delays=0.02/0.01/0/0.13, dsn=5.3.0, status=bounced (service
 unavailable. Command output: Failed to set recipient: Mailbox unknown.  
Either there is no mailbox associated with this name or you do not have 
authorization to see it. 5.1.1 User unknown,
 code=550, original code 550)

This is correct, there is no mailbox "beta at domain.b" as this is only an alias. 
This also happens when I don't use an alias but a distribution list.

Why does postfix and co does not know that a special alias belongs to a 
special mailbox?

Anyone?

  Bye Thorsten