In this paper, we present a method for the automatic extraction of numerical fields (ZIP codes, phone numbers, etc.) from incoming mail documents. The approach is based on a segmentation-driven recognition that aims at locating isolated and touching digits among the textual information. A syntactical analysis is then performed on each line of text in order to filter the sequences that respect a particular syntax (number of digits, presence of separators) known by the system. We evaluate the performance of our system by means of the recall precision trade-off on a real incoming mail document database.