New lists by default allow anyone to subscribe to them with a double opt-in confirmation flow. This is how most public lists work, but isn't suitable for more private or local groups, so we offer a two mechanisms to control subscription.

1. Closed subscription: Set the `subscribe-mode` setting in your List Config to “closed” and subscribers will be sent an “admin approval is needed” message.
   • By default we send a generic “request has been forwarded” sort of message to anyone trying to subscribe. You can customize this message by adding your desired text to the “closed-subscribe” file.
2. By ACL: For advanced users! For groups where you know the intended potential audience, you can require that subscribers belong to a particular (set of) domain(s) by adding it (them) to the subscribe-acl file. For example, if you're running a school list and only want your students to be able to subscribe to it, add `myschooldomain.edu` to the file and only those with matching email addresses will be allowed to subscribe.