Email account forwarders
Forwarders allow you to send a copy of all mail from one email address to another. Email forwarding can also redirect email going to one address and send it to several other addresses without the sender knowing. It can also forward email going to several different addresses to a single email address. You can forward emails to any address, not just those under your own domain name.
If a mailbox exists for the forwarded address, mail will still be delivered to the mailbox as well as being forwarded.
Email can also be forwarded to a special :fail: address - this in effect discards the email, and is useful if you receive lots of spam at a particular address.
Email can also be forwarded (or "piped") to a program or script for processing...
Email domain forwarders
In addition to forwarding individual email accounts, you can forward all email from one domain to the same address on another. For example setting up a domain forwarder from mydomain.com to myotherdomain.com.au means that any email sent to firstname.lastname@example.org will also be forwarded to email@example.com
Note that forwarding a domain's email will override the default address for that domain.