to allow an alias to be associated to more than one email account.
It's an useful (and optimal) way to associate more than one organisation account to an external (public official) email alias.
EG
internal account 1: john@myorg.net
internal account 2: mary@myorg.net
internal account 3: jules@myorg.net
public account (showed in websites, company papers, etc.): sales@myorg.net (this is the alias, not an real email account).
If John and Jules are the sales officers, it would be useful to link the alias to both accounts.
Note: It cannot be implemented using forwarding in a clean way.
Because the mail engine forwards the mails to John and Jules but the headers are tricky: the local account (sales@myorg.net) is masked under the text name of the actual sender. If "sender@anotherorg.com" sent a mail to sales@myorg.net, John and Jules will receive an email from sales@myorg.net ONLY LABELED AS sender@anotherorg.com. This leads to confusion when replaying (john and jules will be replying to sales@myorg.net).
Thank you!
When forwarding mails through a forwarding list, the sender remains unchanged. Replies to a forwarded mail are not sent to the forwarder, but to the original sender. Also, there is such feature like ambiguous aliases in mail servers like Postfix. The current solution of using forwarding lists is the correct technical approach.
-- PD