From PHLster's FB group, the emails went out in batches according to sign-up, and once the run was sold out, no more emails were sent. I also signed up for the second drop too late to get an email.
More drops are coming, and eventually I have to imagine that Enigma will be a regularly stocked item. My understanding is that if we didn't get an email on the second drop, that we're still on the list to get emails when the next drops occur. Hope this helps!