Dear all,

1. My zimbra 7.1.1 opensource edition has 500 user accounts under a domain called someexample.com. But daily there are about 400 spam mails gets relayed by my mail server goes out from<> address. This information I got from daily mail report. But I can't trace the from address. When I see /var/log/mail.log I can able to see lots of mail from swderfhy@aol.com, denvhruf@aol.com, njyhfifkcvj@yahoo.com etc., going out from my mail server. We asked all our users to change their passwords with 10 characters and symbols and numbers. but still we cannot stop that mails. How to block this?

2. I already said that we have 500 user accounts under the domain someexample.com. How to make my mail server to validate and send mails only from those 500 accounts. ie) When a user tries to send a mail, our mail server should check the from address and if the from address is one of the valid accounts of our mail server then only it has to allow the mail to go out. Otherwise it should simply reject it.

output of my daily mail report.

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top 50 Senders by message count
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400 from=<>
384 trusteduser1@trusteddomain1.com
312 trusteduser2@trusteddomain2.com

top 50 Senders by message size
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695m trusteduser1@trusteddomain1.com
270152k from=<>
176561k trusteduser2@trusteddomain2.com

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