The %forward% link is a great way to encourage the forwarding of your email campaigns to colleagues, friends & family.
You need to be using our system Editor templates (NOT Free-Form) in order to have that function in your Editor toolbar. You can see that Forward to Friend choice on the Quick Links drop-down menu within the toolbar.
Hint: my favourite way of using this link is to write some lead-in text e.g. "if you would like to forward this email please click here", highlight that text, click on the link icon (chainlink), select protocol Other, then insert %forward% into the URL box > OK > Save
In that way the link is neatly embedded behind the scenes, rather than producing a line or more of clickable characters.