I have zimbra version 5.x instaled in my work, everyday my zimbra suffering spam relay, I caught the logs of sniffer and threat machine tries to relay with script below:
cG9zdG1hc3Rlcg== or YWRtaW4=
235 2.0.0 Authentication successful
250 2.0.0 Ok
mail from: firstname.lastname@example.org
250 2.1.0 Ok
Someone have this experience?
someone must be able solve this?