[MM3-users] Add domain to Mailman, can't create list with that new domain

I'm testing locally to try and support additional domains.

I can add new mailing lists with a domain: announce-123@mydomain.com I can't add a new mailing list with an alternate domain: announce-123@testing.com

Following the documentation for domains I'm able to successfully add the new domain (locally) with the following steps: https://docs.mailman3.org/projects/mailman/en/latest/src/mailman/model/docs/...

1. Shell into the mailman server
2. Shell into the mailman Python environment: mailman shell
3. Add a new mailing list. from mailman.interfaces.domain import IDomainManager from zope.component import getUtility manager = getUtility(IDomainManager) manager.add('testing.com') show_domains() # with method from the above documentation URL <Domain testing.com> <Domain mydomain.com>

But then when I run a cURL command (from the mailman server) to add a list with that new domain I get an error: $ curl -k -u restadmin:restpass -X POST -H "Content-Type: application/json" --data '{"fqdn_listname": "new-list@testing.com"}' https://0.0.0.0:8001/3.1/lists {"title": "400 Bad Request", "description": "Domain does not exist: testing.com"}

Am I doing something wrong, or missing a step? If not, how do I add support for additional domains such that I can provide mailing list support for that domain?