Do you think perhaps twitpic uses a dynamic email addresses? I would like to build a different service but with the same concepts. User sends an email with their submitted photo and the image is added to the users account.
I'm looking for a place to start. I was thinking that perhaps an email server would handle the image with a post processing routine. When the user for twitpic signs up, might they be assigned a new email address under their domain. Or perhaps the email server looks at some dataset when the email is received to in order to determine whose account the image is to be assigned to. I was hoping highscalability.com would have an article about them, but no.