I would like to know what others are doing to fight spam for the users on your zimbra server. Under the Genral Settings -> MTA I have a checkmark next to Sender address must be fully qualified and then a checkmark next to Dender's domain (reject_unknown_sender_domain). I also have only one RBL which is barracudacentral.org

When I hear about someone having issues in receiving emails I tend to work with someone at the receiving end to get DNS configured properly so the emails can be received on the server.

I have had a few cases where The Forward DNS Entry of the mail server and the Reverse DNS Entry of the mail server do not have the same IP Address and the server says cannot find your hostname. Do these checks want the forward dns name and the reverse dns name to be the same ip address?

What do others do to reduce the amount of spam.