Quote:
Originally Posted by snake_eyes  I'm receiving a lot of messages (return failure), someone is using my mail.domain.com to send spam mails, so how I can take the necessary action with matter? |
You've given no examples of what the messages are, no headers or other information. If they really are NDR then search the forums or wiki (or google/yahoo) for backscatter spam, this is not someone using your server but rather someone using NDR as a means of getting mail to you. You should also look in the wiki for details on improving the anti-spam system - you are using 'smtpd_reject_unlisted_recipients yes' aren't you? This is not a Zimbra problem but rather a side effect of running a mail server.
Further details and reading:
Spam Links - backscatter ndr spam - Yahoo! Search Results