15. A non-transitory machine readable storage medium having instructions stored thereon which, when executed by one or more processors, cause the one or more processors to perform the operations of: receiving user input from a user; in response to the user input, accessing a plurality of electronic mail messages (emails), including a certain email, that are part of an email conversation; extracting content from each of the accessed emails, including the certain email; automatically generating a composite email which includes the content extracted from each of the accessed emails; obtaining a set of markup information indicating one or more markups that were previously made to the content of the certain email, wherein the set of markup information is separate from the content of the certain email; and applying the one or more markups to the content of the certain email to derive a marked up version of the content of the certain email in the composite email.
15. A non-transitory machine readable storage medium having instructions stored thereon which, when executed by one or more processors, cause the one or more processors to perform the operations of: receiving user input from a user; in response to the user input, accessing a plurality of electronic mail messages (emails), including a certain email, that are part of an email conversation; extracting content from each of the accessed emails, including the certain email; automatically generating a composite email which includes the content extracted from each of the accessed emails; obtaining a set of markup information indicating one or more markups that were previously made to the content of the certain email, wherein the set of markup information is separate from the content of the certain email; and applying the one or more markups to the content of the certain email to derive a marked up version of the content of the certain email in the composite email. 20. The machine readable storage medium of claim 15 , wherein obtaining a set of markup information indicating one or more markups that were previously made to the content of the certain email comprises: receiving a markup side mail from a participant of the email conversation, wherein the markup side mail includes a set of markup information indicating one or more markups made by that participant of the email conversation to the content of the certain email; and extracting the markup information from the markup side mail.