Tell them to leave a comment/message with the address. Use a Yahoo mail account and add them all to your contacts I suppose. Then just send it to everyone. I don't know any other way to do this easier, but I'm sure there is one.
my advice would be to use something like google groups

unless you have your own hosting and a knowledge of php which i guess you dont.

google groups is easy to set up anfd lets u sedn out emails to every1 who joins with their email

im guessing it also has widget things u can have up on ur myspace where people can auto opt in by just writing their email in a small box