How to dynamically set unsubscribe link in sendgrid using PHP / Laravel
I ended up setting the substitution text via sendgrid.com and setting the link in my HTML like this <a href="UNSUBSCRIBE_LINK">Unsubscribe</a>. Specifically, on the subscription tracking section on sendgrid.com, I set REPLACEMENT TAG to UNSUBSCRIBE_LINK. So Sendgrid parses your email's HTML and substitutes the hrefs. Pretty cool.