Self-Service allowlist
This list is the first layer of security for any interactions with MailFlow Relay. By default only emails on the allowlist can create an account interact with the email API. An email on this list can be thought of as being a sort of "lightweight account" that affords all access grands a normal user has without the overhead.
Why?
MailFlow Relay is primarily designed to be used inside of defined user groups. As such we assume that all email addresses of members are known (eg. via the member list). This allows us to use a flow that looks like open signup (no passwords or notice to admins needed) without having just anyone open accounts on the instance.
List management
The list is just a long list of email addresses stored in the database and presented as a textbox. you can fdreely edit this textbox and the server will push added records and delete removed ones upon saving.
There is no artificial limit on the size of the allowlist.
Disabling the allowlist
Make sure that public lists do not allow anonymous sending. while we very much do discourage unfiltered public lists we do technically support them for completeness sake. You are now basically running an open relay.
Per list
It is very much not recomended to do this but if needed there is the possibility to diable the check on a per-list basis which enables anyone to use the email API to subscribe to this public list.
Public lists are at higher risk of generating bounced emails. The bounce handler prunes these from lists but it may still negatively impact your spam-scores.
Globally
You can diable the entire feature in the configuration
It is possible to disable the check globally which allows anyone to sign up. This is almost never a good idea unless you know what you are doing.