I have a big problem! It seems like my Server is used to send Spam-Mails!!
How is that possible?! I thought that I have to login/authentificate as a known user to zimbra so that it's possible to send an email - istn't that true!?
When I look into the Admin-Interface the "sender address"es are NOT users of my machine - how am I able to stop others (foreingers) sending mails via my system???? (currently there are about 14500 Mails in "Active" Mode!!!)
Urgent help needed....
Version 4.0.0 for Debian.