Uniform handling of opt-in links when clicking the link is no longer necessary
Just got off the phone with someone at 1ShoppingCart. I was told this is expected behavior and not a bug. I have no idea why it isn't a bug. It ought to be.
If someone joins our mailing list, they get a message with a link to confirm they want to join. If they click the link, it confirms them and forwards them to the "Opt-In Message Thank You URL". If they click it five more times, it always just forwards them to the same thank-you url. This is perfectly fine. Even though the extra clicks don't need to do anything, the system looks like it's performing normally.
Now, if someone purchases a product, that also confirms them. It's another situation where someone doesn't need to click the link anymore. But in this situation, if they click it anyway, they get a very unfriendly "Sorry, you have followed a malformed or expired link" error. This is bad. It looks like the system is broken when really they're already in.
So to recap, there are two ways they might not need to click the link anymore: 1. They already clicked it, 2. They bought something. The situation where they didn't pay us money just silently forwards them to the thank-you page anyway. But if it's because they paid us money, they get a very confusing error which is a much worse outcome. Paying customers deserve a better experience. Both situations should be handled the same - just forward to the thank-you url.