A messaging system (1) comprises a server which registers (2) clients (users) and stores uploaded contact data in contacts databases (11). The contact databases have meta data including profile attributes indicating the subject matter profiles of the contacts. A content manager (25) 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 (25) automatically identifies relevant content items according to the profile attributes, and a messaging engine (21) sends a message with a wrapper having links to these content items. When the contact responds, a response management function (22) captures response data and instructs a build engine (20) to build content from the identified items. The content is then sent to the contact.