The present invention provides a method and system for integrating a composite message such as a Multipurpose Internet Mail Extensions (MIME) message. A metadata template associated with a metadata XML object is extracted from a content management system, whereby a key of the metadata XML object is passed with the request for communicating the composite message. One or more content assemblers are configured to retrieve one or more static content from one or more content management systems and one or more document management systems, in an iterative manner, based on the metadata template. A child content assembler is further configured to extract the dynamic content required for merging with the retrieved static content, to generate one or more message parts. A message generator is configured to concatenate the one or more message parts in a sequence for generating the composite message.