Help with spam control

[klnasveschuk]

I'm having a real problem with spammers sending to reciepients in our domain without an MX record. I want to enable reverse lookups to limit some of this. Here's some background on this:
Currently running Network Edition 5.0.11 on Ubuntu 8.0.4 64bit
We have a split domain with separate outgoing smtp server

Each box that handles mail has an MX record in our DNS.

I would like to continue to allow authenticated users to be able to send remotely through Zimbra.

Will enabling DNS lookups in Global settings and for the server allow above?

[uxbod]

What restrictions do you currently have in place ?

su - zimbra
zmprov gcf zimbraMtaRestriction

have you also had a read of Improving Anti-spam system - Zimbra :: Wiki.

[klnasveschuk]

zimbra@mail:~$ zmprov gcf zimbraMtaRestriction
zimbraMtaRestriction: reject_invalid_hostname
zimbraMtaRestriction: reject_non_fqdn_sender

[uxbod]

Within the Admin GUI you should be able to enable reject_unknown_sender_domain which will do what you are after. I would also highly recommend that you implement some RBL checking aswell.

[klnasveschuk]

Anyone using a rbldnsd with Zimbra?