Abstract: Relevance Theory proposes that communication is an ostensive-inferential process and the communicator,therefore,should provide the most relevant information so that the audience can understand the communicator's intention with the least processing effort.Using a relevance theoretical framework of analysis,the paper first elaborates the application of vagueness in business correspondences and then explores how,in the real business correspondences,vague expressions allow a writer to convey the communicative intentions precisely by processing correctly the optimal relevance.