Beside the possibility of adding an unsubscription link to the footnote of your emails, it can be advantageous to also add a subscription link to your email newsletter. This link can only be added to one newsletter, to ensure the system does not have difficulties identifying duplicated profiles which have subscribed twice.
Add some terms to your newsletter, which allows the customer to recognize the option to (re-)subscribe to your newsletter. Then add the link. Highlight a specific part of the text, which you want to make "clickable" and a toolbar will appear. Click on "Special links" and in the following drop down menu, select "Subscriptions" > "Subscription link". You will now be able to see that the selected text has become clickable; it will be underlined and in a different color. You have successfully added your subscription link!