Update a subscriber

Sets whether this subscriber is on the list. Needs audience: write, and is a write.

status is the whole of what this writes, and only two of its five values can be sent. bounced and complained are verdicts a mailbox provider reached, so setting one would be asserting somebody else's answer on their behalf, and pending belongs to a confirmation flow nothing in this API starts. The address is not writable either: it is the subscription's identity, and on a subscriber with a Commune account behind them it lives on that account rather than here. Add the right address and delete the wrong one.

Both directions publish:

• To unsubscribed: subscriber.unsubscribed with reason: removed, which is the reason that means the newsletter did it rather than the reader. The row survives, so bounce and complaint history is kept and GET goes on resolving them.
• To subscribed: subscriber.created with resubscribed: true, exactly as a reader coming back publishes. Automations treat it as not a new subscriber, so nobody is welcomed again.

Setting the status it already has succeeds, changes nothing and publishes nothing. Setting subscribed on a complained subscriber is refused with 422: only the reader can undo a spam complaint, by subscribing again themselves.

Unlike Add a subscriber, this does not change source. A subscription imported from a provider and reactivated here is still an imported subscription, because what moved was one column of an existing row and not a new subscription being made.