Hello @JanB590. We have a new feature in accounts that allows you to easily resubscribe to a mailing list. Under Contacts, search for your email address and click on your profile. You will see a link that says Resubscribe.
You will click on this, select the list(s) you wish to add yourself back to, check the permission box, and click Send Email. You will receive a confirmed opt-in email at that address and once you click on the link in the email, you will be added back to the list.