Litmus.com, a web application used for email testing, used to cause problems while testing unsubsribe emails (one-click opt-out) during tests, as it in good faith “clicks through” all email links (including links to unsubscribe) and as a result it unsubscribed itself without fail. Therefore it was necessary to remove the static test address from the suppression sheet before another test was carried out.
We were trying to sort it out with their technical support, which at first claimed they were trying to recognize the unsubscribe link by its link text. Then we sent them all possible forms of “Unsubscribe” in Czech to finally acknowledge that this was not the way to solve this issue.
In the end they added a unique identifier for unsubscribe links: if you add a text into tag <a> data-litmus-ignore, Litmus will skip this link when testing. When in use, just rewrite our Unsubscribe (Odhlásit) button, Cancel the newsletter (Zrušit odběr novinek) button, Log out (Odhlašte se), etc. in the following form:
<a href="unsubscribe_link.cz" data-litmus-ignore>Unsubscribe</a>
And that’s it. From now on your Litmus will no longer unsubsrcibe itself, regardless of the exact wording of the text.