Meh, you don't need to sign in, it doesn't say that you need to.
btw, the xxxx's mean your mobile number!
Forgot to mention that, so if your number was (123) 456 - 7890
you'd do tis for the email addy:
Email:
1234567890@message.alltel.com
(Since most carriers have a word limit, try and keep everything to a down count)
Subject:
P
Body:
I
Attachment:
YourMilkJugs.