To set up a rule to forward your mail from Fastmail to another email inbox, do the following:
- Open the Settings → Filters & Rules screen and click New Rule in the toolbar at the top.
- In the Conditions section, click The sender's email and change this to All messages.
- In the Action section, select Send a copy and enter the email address you want to forward to. To send to multiple addresses, separate the addresses with a comma.
- Click Save in the toolbar at the top.
You can also use rules, so messages will only be forwarded if they follow certain patterns. Note that a forwarding rule will not apply to any message caught by discard rules, or any message filtered as spam.
If you just want to forward all mail sent to one of your aliases, you can do this by directly setting the target of the alias to the address you wish to forward to.
The main differences between this approach and using a rule are:
- The alias forwarding is only possible on an alias, not email sent to your main address. If you want to forward email sent to your main address, you have to use the Settings → Filters & Rules screen.
- The alias forwarding will apply to all messages sent to your alias. There's no way to only forward emails that only meet a particular criteria.
- Forwarding emails through aliases will mean that spam protection is not run before these messages are sent out. If you would like the messages to be run through Fastmail's spam filter first, forward them by creating a Rule.
If these limitations on virus, backscatter, and spam filtering are OK, then you can use the Settings → Users & Aliases screen to target aliases at the external address(es).