The analytics to measure the success of an email campaign should include: open or view rates, click through rates, the number of pages viewed, the duration of the site visit, the number of contact forms submitted, the number of phone calls received, revenues and roomnights from special rate code bookings or packages purchased, and the long term sustainability of the campaign. Do people print out the email and present it by mail or at the front desk when making a reservation? Have you received inquires referencing the special rate announcement?