Can we add custom variables to the subject line in Kartra emails? For example, Subject: “Confirmation – {first_name} {last_name}”

Yes, you can add any of the Kartra dynamic variables into your email subject lines (both broadcasts and sequence emails).

Please note, if you use the dynamic variable for {first_name} and have any leads that have not given you their first name, the dynamic variable will show as Anonymous. 😳 So only use this dynamic variable if you require the first name be filled out by all of your leads.