is it mean my server is setup as open relay ?I'm using zimbra version 5. How can I trace whether the spamming is from local zombie machine or from outside?
I have read the document.It says that this method can be spoofed by forging the mail from: header (so mail appears to original from within the domain), so it isnt foolproof, but it works for basic needs.
May I know is it workable for me?
My situation is as below:
all the spam mail reaches our users mailbox by using our local distribution list as sender and recipients.
like sender:
all@mydomains.com recipients:all@mydomains.com