I have been using zimbra CE since version 6 and now 7, unfortunately my server is used to send spam with valid user accounts.
When we checked the user account involved in the zimbra web client, we find that they have changed the firm, the forwarding address, I guess Trojan virus is on the user's computer, but still do not understand how it works, because at times when your computer is off there to send spam.
Therefore do not understand how is that spam can be sent and if there is how to configure zimbra to stop this from happening.
Try changing the configuration of postfix with no results.
check_client_access hash:/opt/zimbra/postfix/conf/misclientes, permit_mynetworks,
reject_rbl_client list.dsbl.org, permit
contenido de /opt/zimbra/postfix/conf/sender_access
/@mi\.dominio\.edu$/ 554 No uses mi dominio para enviar correo
contenido de /opt/zimbra/postfix/conf/misclientes
contenido de /opt/zimbra/postfix/conf/misremitentes
/.*/ 554 La direccion remitente debe ser local
Already saw that my server is not Open Relay,
The SPF settings help? as I can do this in zimbra?
Thank you very much.