Aer Lingus and easyJet sent emails every three days to customers that had booked a flight during December 2015, according to a new report from IdeaWorksCompany. The company analyzed the email marketing of six airlines after booking a flight during the busy travel month. They found that AirAsia sent only three post-booking emails. Ryanair sent the least emails and had the lowest average word count at 222 words per email.