Here is the fix, add list to list must be out side of the loop
add list to list(%emaill, $list from file("D:\\email.txt"), "Delete", "Global")
Loop(100) {
set(#username, $account data("Username"), "Global")
type text($element offset(<username field>, 1), #username, "Standard")
change dropdown(<birth month dropdown>, "Random - Skip First Choice")
change dropdown(<birth day dropdown>, "Random - Skip First Choice")
change dropdown(<birth year dropdown>, "Random - Skip First Choice")
type text($element offset(<password field>, 1), "