Marketo not recognizing custom unsubscribe link in emails

Hi
We are trying to use custom unsubscribe link in our emails using snippets. But Marketo is not recognizing the presence of it and is inserting the default unsubscribe message at the bottom. 
Is it because I haven't deactivated the default link in Admin > Email? Do I absolutely have to remove it for the emails to only show the custom unsubscribe link?