java security session

Question

hello community , i am learnin java , i use this part of code to create a session for my application , here is my code , when i run it , i get a drop-down list that contains my email adresses  that i already use on my pc and emails adresses that i use for testing my application , one of this adresses  i have never  used mn my computer not even for the test , but it is on the list , can you explain to me please why ? is it that a relation with the security of my pc