A recent study by Customer Growth LLC published by The Wise Marketer tracked the quantity and content of frequent flyer email sent by five programs, American Airlines, Delta Air Lines, US Airways, JetBlue and Spirit, over a six-month period. The study looked at the volume, purpose, relevancy and personalization of email communication. On average, members received just under five emails per month. The largest amount of emails — 65 percent — contained fare or credit card promotions while 25 percent addressed membership issues and 12.5 percent were sent in response to a recent transaction made by the member. The study concluded that the amount of email sent was reasonable but suggested that the airlines could become more effective by tailoring their messages and offers to the individual needs of members.