i have a set...which a little bit different than usual...i have an SMTP server as smtpout, which has an anti-virus/spam appliance as relay-host.
so the scenario is like this
mail-client ---ConnectTo--> ZimbraSMTP ---ConnectTo--> AntiVirus Appliance.
the problem is, the email client connects to my SMTP server, and after SASL authenticating with user email@example.com, the relay is enabled, and the client can send emails using (firstname.lastname@example.org).
Is there any way to disable that kind of spoofing on zimbra ?