As is alluded to in T60373, WMF used to host our own unsubscribe form. There were some repeated bugs in December 2013 - January 2014, and we decided to use Silverpop's form as an emergency measure. 2 years later, we're still using it. The form is fine, but the url is:
https://www.pages04.net/wikimedia/WMFUnsubscribe/ ---- not a Wikimedia domain (Silverpop can't offer us a page at our own domain over https).
Now that we have our nifty click tracking system, we have wrangled almost all of the domain issues related to our emails. Is it possible for fr-tech to host our unsubscribe page again, so all of the links in our emails come from the same domain?
As a suggestion, Silverpop's forms can be embedded onto one of our own pages, so if needed, unsubscribes can continue to go through Silverpop's form. We just have to host the page in as many languages as we email, and make sure there is some sort of form validation.