1. A method of presenting extensible emails from a third party to a user, comprising the steps of: (a) receiving an extensible email from the third party via a service provider which provides email service to the user, the extensible email including metadata listing a URL of a server controlled by the third party, the URL having code for generating an interactive view for the email; (b) checking whether the URL points to a web address inside a firewall of the service provider; (c) if the URL points to a web address inside the firewall of the service provider, taking no action with respect to accessing the URL; (d) if the URL points to a web address outside of the firewall of the service provider, fetching the code from the URL listed in the metadata in response to interacting with the email received in said step (a); and (e) if the URL points to a web address outside of the firewall of the service provider, running the code to generate an interactive view in the email, including the step of running the code in a secure sandbox which isolates the code and prevents the code from adversely affecting at least one of the service provider presenting the extensible email and a user receiving the extensible email.
1. A method of presenting extensible emails from a third party to a user, comprising the steps of: (a) receiving an extensible email from the third party via a service provider which provides email service to the user, the extensible email including metadata listing a URL of a server controlled by the third party, the URL having code for generating an interactive view for the email; (b) checking whether the URL points to a web address inside a firewall of the service provider; (c) if the URL points to a web address inside the firewall of the service provider, taking no action with respect to accessing the URL; (d) if the URL points to a web address outside of the firewall of the service provider, fetching the code from the URL listed in the metadata in response to interacting with the email received in said step (a); and (e) if the URL points to a web address outside of the firewall of the service provider, running the code to generate an interactive view in the email, including the step of running the code in a secure sandbox which isolates the code and prevents the code from adversely affecting at least one of the service provider presenting the extensible email and a user receiving the extensible email. 3. The method recited in claim 1 , further comprising the step of comparing the portion of the code against one or more predefined policies regarding execution boundaries for the code to determine whether the portion of the code will adversely affect a service provider presenting the extensible email or a user receiving the extensible email.