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?