>>>>> "Claudio" == Claudio Corvino <c.corvino81@gmail.com> writes:


> I have an external MTA configured with Postfix that delivers email to an internal IMAP/LMTP
> Dovecot server configured to bind an LDAP to check if users exist.

You should have postfix do the checking for whether or not users exist
and then have postfix reject and deny the message.  Then you don't
care because the IP of the postfix server is almost certainly your MX server.

> If the user does not exist, my MX sends a non delivery notification,
> and into the e-mail there's the local IP address of the Dovecot
> server.

> I can't find a way to remove or hide that IP, here is an example of line that contains the IP
> (with X) that I would like to hide/remove:

> "The mail system

> <user@domain>: host hostname.domain.com[XXX.XXX.XXX.XXX] said: 550"

> Thanks in advance!

> Cheers

> --
> Claudio