We would recommend you too add the URL to your email template on the top of the page. This is because some email providers are older or choose to display your email in a different way. You can easy add the link to the email template by adding a merging code behind your text:
As this is a merging code the link will not work in the generated URL of the campaign, and not when distributing test emails. You will have to do a full distribution to test this.