it really depends on how the organization's legal counsel interprets the laws and how risk-averse they are. Some organizations might say only Germany requires double opt-in, while others also include Austria and Switzerland. Some organizations might say the US operates under "everyone is opted in until they opt out" while others might say everyone needs to opt in, regardless of country.

I've just experienced the same issue with confirmation links being executed in a sent email before the user has received them and invalidating the link. I got around the issue by modifying the page the URL links to. I've added a Confirm button on the page which the user has to click to confirm their email and this works nicely.

If the link you are trying to send is just some kind of harmless confirmation link (e.g. subscribe/unsubscribe from a newsletter), then at least use a form inside the web page to do the actual confirmation through a POST request (possibly also using a CSRF token), otherwise you will unequivocally end up with false positives.

Confirmations are a little more difficult, as senders really do want to keep the transaction as low friction as possible. Adding a confirm button may result in people abandoning the confirmation process.

This behaviour may affect opt-in confirmation links.

So The Screener really just acts as a second layer of consent—almost like a confirmed opt in.

The difference is that this happens in the email client, not at the subscription step. Why is this a big deal? Because, even though they just subscribed to your email, there’s a chance your email won’t get a thumbs up.

We got this email from Parabo, the print shop app, and smiled. Instead of the very standard “Please confirm subscription” header text, we were greeted with a funny, whimsical hello that’s totally in their brand voice. “We really want you to want us” is a clever way to break up the usual mundane greeting, and, guess what? It totally reaffirmed why we thought we wanted to sign up for their emails in the first place.

The blog A Life Of Productivity uses double opt-ins to make sure that people signing up for the email newsletter really want to read it. If a site visitor was somehow subscribed by accident, the subscription won’t go through unless they click the verification button sent to their email address.<img class="aligncenter size-full wp-image-32479" src="https://www.convinceandconvert.com/wp-content/uploads/2016/05/A-Life-of-Productivity.jpg" alt="A Life of Productivity" width="724" height="549" />

With this method, you can ensure the email address receiving your communication actually belongs to the person giving the consent and hereby further ensure that you avoid high unsubscribe rates, retain the integrity of your list and the reputation of your address. This method of registration is considered best practice in many countries, especially Germany and in the EU in general.