[Mailman-Users] Getting started with Postfix virtual domains

[Brian Parish]

I have been hosting using Postfix for a while now, but am just setting up 
Mailmain for the first time.  Following the installation instructions, I am 
breaking postfix when adding the virtual-mailman entry to my 
virtual_alias_maps line in main.cf

This is obviously because at this point virtual-mailman.db does not exist, but 
I don't see a step to create it.  Presumably I am missing the bleeding 
obvious here?

TIA
Brian