AFAICT, if a user gets removed from a list, they cannot be re-added to the list via the API.
We can see, however, what's being reported back in this situation.
Status code 400. "400: Forgotten Email Not Subscribed user@user.test
was permanently deleted and cannot be re-imported.
The contact must re-subscribe to get back on the list."
Instead of this message ...
There was a problem with your newsletter signup
... it'd be beneficial to add some additional context for this use case.
Closed: won't fix
1.0
User interface
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
Thanks for submitting this ticket — and sorry we didn’t get back to you about it sooner. We are cleaning up old issues and issue for old versions and are going to close this one. If this issue is still relevant for you, please re-open it and update the “Version” field, and include any updates to the behavior you are seeing.With a smaller issue queue, we’ll have an easier time getting back to you.