Virtual aliases can map to addresses that do not terminate on the local system while regular aliases can only map to addresses which terminate on the local system. Virtual Alias Domains You will need to add these lines to the main.cf file. virtual_alias_domains = example.com If you were going to add a number of domains you would want to create a map file.  Create the file /etc/postfix/virtual_alias_domains and enter one domain on each line ...

Mailbox Ownership The mailboxes must each be owned by a user and connected to a group on the system. There are two directives which determine the ownership of mailboxes for users and groups. virtual_uid_maps virtual_gid_maps It is possible to set a static map which means that one user will own all of the mailboxes of one domain. If you were setting up a static map with an account called vmail which had a UID of 1023 and a GID of 1024 you would ...

Postfix Mail Server will allow you to set a base domain and add any number of virtual domains.  Virtual domains can either be virtual alias domains which are the domains that your server is the final destination for and also virtual mailbox domains which do not have local accounts and only pick up mail through IMAP or POP3. The ...