You can do something different with a similar result using Fastmail (
https://www.fastmail.com). Set MX in the domain DNS to target the Fastmail incoming mail server. Then in Fastmail you can set each alias to target one or more destination systems.
So you could set
info@alan.org to be delivered to a gmail account,
enquire@alan.org to be delivered to another host account, and
misc@alan.org to be delivered to both gmail and Fastmail accounts.
This alias targeting works as long as the domain is under the control of the user and has the MX set to deliver to the user's Fastmail account. The user's Fastmail account is then hosting the mail delivery for that domain.
Bill