In this paper we present a new postal envelope segmentation method based on 2-D histogram clustering and watershed transform. Segmentation task consists in detecting the modes associated with homogeneous regions in envelope images such as handwritten address block, postmarks, stamps and background. The homogeneous modes in 2-D histogram are segmented through the morphological watershed transform. Our approach is applied to complex Brazilian postal envelopes. Very little a priori knowledge of the envelope images is required. The advantages of this approach will be described and illustrated with tests carried out on 300 different images where there are no fixed position for the handwritten address block, postmarks and stamps.