A messaging system comprises a server which registers clients (users) and stores uploaded contact data in contacts databases. The contact databases have meta data including profile attributes indicating the subject matter profiles of the contacts. A content manager receives content items such as collateral parts and message text and stores them in content databases, also with meta data having profile attributes. When a client requests a message to be sent to a contact, the content manager automatically identifies relevant content items according to the profile attributes, and a messaging engine sends a message with a wrapper having links to these content items. When the contact responds, a response management function captures response data and instructs a build engine to build content from the identified items. The content is then sent to the contact.