Hi @samgood1,
If you haven't already we do have a Guide to Template Tags and Variable Syntax if you want to reference as well. You can embed a signup form in that page. Then use your campaign to drive users to that page.
As a note if you are looking to link track, UTM's will not append on links through the preview and it would only work through a live send. It may be prudent to create a test campaign that sends strictly to a list of 1 or 2 people (your test or personal emails) and testing those links to ensure they're returning what you're expecting.
An alternative method to what you're currently doing that may be a bit easier is to create a landing page on your site ( a page that is hidden from public view that you can link users to ). This way, for that campaign you are sending you can link users to that section of your site and only have the form show on that page. This is generally the recommended method we recommend as landing pages are re-usable should you want to pursue a similar method in the future.
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