Merge Tags Help

Hi

I’ve recently secured an advertiser for my newsletter, and they are looking to use a magic link on their ad.

They provided the following instructions to set up (as Ghost doesn’t yet support full Sparkloop integration):

'https://sparklp.co /p/cfbecf7689?email= < EMAIL >

Here’s how to use your Magic Link:

1. Copy your Magic Link and give it to the newsletter creator who will include it in their newsletter
2. That newsletter creator needs to replace the < EMAIL > in your Magic Link with whatever merge tag their email platform uses to dynamically insert each subscriber’s email address
3. Their subscribers will be able to opt-in to your email-list from inside the newsletter with just one click!’

Apologies if this is a silly question and the answer is obvious, but how do I know what the merge tag is or where to find it (using ghost.io)? or will it simply remain '< EMAIL >'?

Thanks,
Keith