I do not know about programing but I would guess that it has more than one variable, the confirmation number & your email adress.
but thoses who didn't entered their email adress & deleted their confirmation number are screwed
but thoses who didn't entered their email adress & deleted their confirmation number are screwed
No, its just a script (Perl, Java, Javascript, etc) that generates the webpage. Same script with only 1 variable, your confirmation number, and the rest is the same for everyone. An email server can easily handle that many emails in a day.