I am looking for a way to have some aliases on my custom domain which need to be forwarded right away.

So for instance I have 'mydomain.com'

person1@mydomain.com is a mailbox and will just get mail delivered

person2@mydomain.com should just be forwarded to person2@gmail.com 

I know I could setup a catch all mailbox and use filters but that requires me to purchase another mailbox.

I could have person2 be an alias to person1, and use a person1 filter, but the filter actions only allow for delete in 1 days or delete (trash), so that mailbox will really notice all the forwards.

As there is no way to add a cheaper plan box or free box to the subscription I am looking for another option