Block non-existing sender domain?

[bhwong]

Is there a way to configure Zimbra to block any sender that try to fake as sender from domains that are not in our Zimbra domains? This will be extremely useful to filter off spams from infected PCs.

Why didn't anyone thought of implementing this???

[phoenix]

Originally Posted by bhwong

Is there a way to configure Zimbra to block any sender that try to fake as sender from domains that are not in our Zimbra domains? This will be extremely useful to filter off spams from infected PCs.

Go to the wiki and look at the ant-spam article.

Originally Posted by bhwong

Why didn't anyone thought of implementing this???

It is possible to do it and you'd have found it if you searched the forum or wiki for an answer. There are also conflicting opinions on whether this is a legitimate technique to add to a mail server - search the internet or postfix documentation if you want more information.

[bhwong]

I have read Improving Anti-spam system - Zimbra :: Wiki many times. It only states black and white listing which is not effective at all because spammers will always keep changing their IP and email addresses.

Blocking all emails send out of our Zimbra server that has sender email address faked outside of our hosted list of domains will be extremely effective. Has anyone manage to get this implemented?

I guess not since I can't find any. So I have proceed to submit enhancement at: Bug 53852 – Block non-existing sender domain.

Please vote for it.

[phoenix]

Originally Posted by bhwong

I have read Improving Anti-spam system - Zimbra :: Wiki many times. It only states black and white listing which is not effective at all because spammers will always keep changing their IP and email addresses.

If these are infected machines on your LAN then you have an internal security problem. Have you checked your LAN for infected machines, have you also removed infections from the, do you check your mail reports for high levels of mail being sent by your users?

Originally Posted by bhwong

Blocking all emails send out of our Zimbra server that has sender email address faked outside of our hosted list of domains will be extremely effective. Has anyone manage to get this implemented?

You didn't mention that these were from your server. I've already asked you to provide log file information, why is it that you're reluctant to provide information that may enable forum members to help? Almost every thread you start has a total lack of information, why is that?