My first is in email, but not in domain names.
My second is in Vex, but not in someone I used to date.
My third is the window to my soul.
My fourth is in Gentle, but not in Nettle.
My fifth is in Vowel, and is one, but isn’t in Consonant.
My sixth is not in to, but is in not.
My seventh is MDMA
My eight is in Riddle, but not in any bowed string musical instruments.
My ninth is in Weight, but not on England’s largest island.
My tenth is in trouble, but not on any Russian coins.
My eleventh is in the world’s largest online retailer, twice.
My twelfth pollinates and bumbles.
My thirteenth is Л.
My fourteenth is 2.71828182846.
My fifteenth is 01100001.
My sixteenth is textually you.

My key which you’ll need, is the Bluebird’s chirp.