Quick way to forward mails via postfix

Source: https://www.bentasker.co.uk/documentation/linux/173-configuring-postfix-to-automatically-forward-mail-for-one-address-to-another

Assuming you’re running Postfix, first we make sure the virtual mappings file is enabled here /etc/postfix/virtual:

# Scroll down until you find virtual_alias_maps, make sure it reads something like
virtual_alias_maps = hash:/etc/postfix/virtual
# We also need to make sure the domain is enabled
virtual_alias_domains=example.com

Save and exit. Next we add the aliases to our mapping file /etc/postfix/virtual:

# Forward mail for admin@example.com to jo.bloggs@hotmail.com
admin@example.com  jo.bloggs@hotmail.com

If we want to send to two different addresses at once, we specify:

admin@example.com  jo.bloggs@hotmail.com jos.wife@hotmail.com

Finally, we need to create a hash (later versions of Postfix don’t require this)

postmap /etc/postfix/virtual

It’s the same principle as passing mail into a local user’s mailbox.