What is Email conversion rate? Email conversion rate is the number of people who took the action you wanted them to take vs the number of people who received the email.
For example, if you sent out an email to 5000 people and only 100 people buy stuff from you, then your conversion rate would be 2%.
Here is the math.
Email sent. = 5000
Sales from email = 100
Conversion rate = 100/5000 = 0.02
Conversion percentage = 0.02*100 = 2.0%