Why do replacement tags like $LOGIN$ and $FIRSTNAME# not work in the communications I send to my clients?

The replacements tags are small pieces of code that need to be typed correctly, exactly as provided in the system. In your examples, the replacement tag for the Login link is in fact $LOGINLINK$ and the replacement tag for the first name of the client needs to start and end with the dollar sign: $FIRSTNAME$ . Also, the letters between the dollar signs need to be always capital letters. And make sure there are no blank spaces inside the replacement tags.