I'm sure they made a huge push with advertisers to get as many emails out by the end of March to make sure that a decent percentage of their subscribers passed the 500 point hurdle by the end of the quarter and thus earn their first reward (assuming that if people didn't earn an award or come close, subscribers would leave in droves). Thus, any advertiser that was even close to considering participating in E-miles probably got some attractive incentives to run early, leaving the "pipeline" of new advertisers that would run in April practically empty. I would assume/hope that the "run rate" of emails returns to normal (whatever that is) by May and will use that rate to judge whether this program is worth the time to continue participation.