About 4-5 years ago, in another lifetime, I remember adding a token to URLs in outbound Marketo emails that would append the LeadID to the URL, so that when the recipient clicked on the URL, it would send their Lead ID back to Marketo, to help ensure we could identifying the recipient, and pre-fill, or prog. profile the form.
For example, if the Marketo cookie was deleted, this would identify the lead record.
For the life of me, I cannot find in the resource files how to do this again.
Is it just buried in &mkt_tok now?