When small and medium enterprises (SMEs) engage in collaborations, they typically rely on E-mail based communication due to limited access to modern technology. One of the key factors to enhance SME collaboration is enabling semantic interoperability at the level of emails and documents that are exchanged between collaborating enterprises. However, achieving semantic interoperability is not an easy task to accomplish. Automatic interpretation of information relies on pre-defined static ontologies shared by diverse enterprises, which in practice is difficult to establish because of the specialized nature of products and services offered by each enterprise. In this background, this paper presents an agent-based negotiation approach for enabling semantic alignment of concepts, and thus facilitating semantic interoperability between SMEs to enhance collaboration.