  Email is one of the most successful computer applications yet devised.
Communication features in email, however, have remained relatively static in
years. We investigate one way of expanding email functionality without
modifying the existing email infrastructure. We introduce email late bound
content, a simple and generalizable technique that defers message content
binding through image lazy-loading. Parts of an email are converted into
external images embedded in HTML code snippets, making it so that email clients
will defer the image download (i.e. content binding) until the moment users
open the email. This late bound content allows email senders and third party
services to update delivered emails. To illustrate the utilities of late bound
content, we present four new example features and discuss the tradeoffs of
email content late binding.
