Each virtual domain has its own alias file. Mail to an address like user@virtual_domain will be aliased in the alias file for that virtual domain. Then each recipient in that virtual domain will be converted into system users via the user alias map. Then final delivery will occur. It is possible to have a virtual domain alias expand to recipients that are in other domains, there are no restrictions of any kind on virtual domain alias files. To edit the alias file for a particular virtual domain see ``Managing Aliases in a virtual domain''.