scsi, your link leads to an old version of that particular DirectAdmin feature. The only way email will get delivered with a domain pointer is if it's set as an alias, which is neither covered nor shown in your link.
However, using an alias results in the entire site being aliased, not just email.
gerbil, if you want the entire site to be aliased you can use the alias form of domain pointer.
If you only want email aliased you can do the following as long as both domains are in the same username and you have shell access. First download all the email in all 123.NET directories, as the following will irrevocably delete any email in the 123.NET domain.
Then ...
shell into the server as the username owning both domains.
1) remove the /imap/123.NET directory:
2) link the imap/123.NET directory to the imap/123.com directory:
Code:
$ ln -s imap/123.com imap/123.NET
If you're using mail to the main username at both domains, they're already going to the same mailbox.
Note that we guarantee work we do, but not instructions we post on these forums. Anything you do, even if you follow directions, could damage your server's contents. We take no responsibility if that happens, unless you hire us to do the work.
Jeff