The aliases provide a system-wide mechanism to redirect mail for local recipients.

The `Alias to...` field contains one or more of the following, comma-separated:

- `address`: Mail is forwarded to `address`, which is compatible with the RFC 822 standard.
- `/file/name`: Mail is appended to `/file/name`. See local(8) for details of delivery to file. Delivery is not limited to regular files. For example, to dispose of unwanted mail, deflect it to `/dev/null`.
- `|command`: Mail is piped into `command`. Commands that contain special characters, such as whitespace, should be enclosed between double quotes. See local(8) for details of delivery to command. When the command fails, a limited amount of command output is mailed back to the sender.
- `:include:/file/name`: Mail is sent to the destinations listed in the named file. Lines in `:include:` files have the same syntax as the right-hand side of alias entries.