On *nix environments it is possible to forward the mail to one account to another user (or another email address if external mail is supported).
This is done by adding the recipient in a file called .forward in the home directory.
Example To simply forward to another address:
user@server$ echo email@example.com > ~/.forward user@server$ chmod go-w ~/.forward
In order to forward to several addresses coma (,) is used as a delimiter between the different recipients.
Example To forward to two addresses at the same time:
user@server$ echo firstname.lastname@example.org,email@example.com > ~/.forward user@server$ chmod go-w ~/.forward