I upgraded to 6.0.5 on the weekend (from 6.0.4) and now e-mails that are forwarded via a filter are sent from the Zimbra account it's self.

Before it would forward the e-mails with the from address being the original sender, this is what I need.

The reason why I forward via the filter rather then using the forwarding options under the account's preferences is that I need the e-mails to be checked for spam before forwarding.