When someone subscribes to your publication, we verify that the basic details of their card are correct, but we don't block the first charge from going through. Payment failures like this are fairly common, and often temporary. So if the initial payment fails, we retry the next day, and often our next attempt will succeed.
If the payment fails again, we will automatically retry and email the user on your behalf, asking them to update. After two weeks and multiple attempts, if the payment still doesn't go through, they will then lose access to your publication.
We do this because we find it significantly improves your conversion rate than if we just blocked the customer up front. In many cases, the retry succeeds. If it doesn't, telling the customer that they're subscribed for now, but we're working out the billing is a better experience than telling them that they can't subscribe at all right now.
If you'd like to reach out to subscribers with payment failures, we've seen that personal outreach from the author can further improve the customer's willingness to update their card or call their bank if they're experiencing issues. But even if you don't do anything, don't worry, we'll keep trying on your behalf.