2. The method as recited in claim 1 , further comprising: determining compensation to be provided to a user of the client computing device for allowing the one or more electronic transmissions to have respective selected one or more advertisements inserted, wherein the determined compensation is based on a bid system and varies depending on hierarchy rankings of the selected one or more advertisements inserted in the respective electronic transmission.
1. A method comprising: accessing one or more electronic transmissions transmitted from a client computing device or ready for transmission from the client computing device; for respective electronic transmissions of the one or more electronic transmissions: scanning content of the respective electronic transmission to identify one or more keywords included in an advertising data structure; selecting one or more advertisements for insertion into the respective electronic transmission based on relationships stored in the advertising data structure, wherein the stored relationships indicate associations between the identified one or more keywords in the respective electronic transmission and the selected one or more advertisements; inserting the selected one or more advertisements into the respective electronic transmission, wherein inserting the selected one or more advertisements comprises changing at least one display characteristic of one or more words already included in a message body or subject line of the respective electronic transmission; and initiating transmission of the respective electronic transmission to one or more intended recipients.