It’s a bit more work than expected but I managed to get it working.
In addition to adding an alias in
/etc/aliases the transport for the user also has to be set to
local and the mailbox needs to exist.
Add a mail user as normal.
transport_maps. It probably doesn’t exist, so add it, for example
transport_maps = hash:/etc/postfix/transport.
/etc/postfix/transport probably doesn’t exist so create this file. The contents are the email user you just added followed by
If it’s not working try
restart postfix service