I host quite a few OSX mail servers (10.4 and 10.6) so reasonably familiar with the setup. I host multiple domains so 'Enable virtual hosting' is enabled and a list of domains is entered below it. Enable virtual hosting: virtualdomain.com Then for each user in the Workgroup Manager I enter a 'Short Name' for whatever alias/domain the user is accepting email. myaccount Short Names: email@example.com Then, under the Mail tab I Enable mail This seems to be enough. Mail that arrives at the server for firstname.lastname@example.org is recognised as being for one of the local virtual domains (as opposed to an attempt to relay to another domain), and matches one of the aliases of an account. It goes into the users account and is accessible via IMAP or POP. I also have relaying restricted to my internal network (123.456.789.0/24). OSX Lion mail server is very similar. It has a place in Server Admin to enter Virtual Domains and a place in Workgroup Manager to enter Short Names (email aliases). However, it has no user Mail tab where I can specify to Enable mail or forward it. I have the same Relay rule. HERE'S THE PROBLEM Mail sent to the server from inside the network is accepted and delivered to the specified account. Mail sent from outside my network is treated as though it was a relay attempt and refused. This is mail to the same address, just originating from outside my network. It is not a firewall issue. I have ensured the server is accessible on port 25 from the outside world and can see the attempt and denial in the server log. It thinks it is an attempt to relay. So the virtual host list is not being taken into account by the SMTP server when an outside SMTP server tries to contact it. Now usually I write one of these long winded questions and by the time I have written 75% of it the answer comes to me and I just delete it. Not the case in this instance. So I would love to hear any other views or ideas on the differences in Lion mail server.