1. A computer-based method for providing additional content in an email, comprising: identifying metadata of the email received at an email server, the metadata being indicative of a parameter used to retrieve the additional content, the identifying metadata including at least: analyzing the email to identify a partner content provider; and analyzing the email to identify metadata associated with the partner content provider; providing the metadata from the email server to an email client prior to the email being opened by the email client; returning a first instance of script code from the email server to the email client in response to receiving an indication of the email client accessing the email, the first instance of the script code providing a first state of the additional content; returning a second instance of the script code from the email server to the email client in response to receiving a second indication of the email client accessing the email, the second instance of the script code providing a second state of the additional content, the second state different than the first state; and providing at least one of the first instance or the second instance of the script code for hosting in an inline frame (iframe) of a user interface (UI) of the email client such that the additional content appears to be part of a message content of the email.