you have left the filed next to the equals condition blank
by leaving that blank, you are sending the email to all users where the UserEmail column does not have a value:
UserEmail = ""
for the UserEmail column, you should probably not be using the equals condition.
perhaps use the begins with, or ends with condition.
lets say I had 3 users in my table with the following email addresses:
if i set the audience up as "ends with" "yahoo.com", this would target 2 users:
if i set the audience up as "begins with" "john", this would target 2 users as well: