How to know which email booked a call automatically

When a contact schedules a call with us from an email, we would like to know which email that happened from without having to dig through their contact record. An updated field would be ideal with the subject line of the email.

Currently, we have a tracked link we use in our emails to schedule, then once they schedule they get a tag from Zapier. And we have an email lead source automation that updates the lead source to "email" when those two things happen.

But we have to dig through the record to see which email they clicked to produce the call. It takes quite a bit of manual effort. There's got to be an easier way!

Thanks for your consideration and help with this.