sending too much will be spam
email lasts longer than Facebook, in case there is another more-famous FB come out
call to action - read more, find more, shop now, sign up now
click through rate - count from click on email
landing page page that appear after the click
conversion rate- % of respond
bounce rate
hard bounce- that email is no longer be used
soft
A/V testing- message A to group a message B to group b to look at the resul