the invention provides a system and method for the automatic detection of items as originating from a specific source , e . g . client or customer , identifying specific characteristics of the items , comparing these characteristics to a database of sets of such characteristics identified with or more sources , and providing an output of items that match the characteristics . in one embodiment of the invention , a mailer detection and manifest system detects mail pieces that were sent by specific mailers using mail piece characteristics that are unique to the mail pieces of each mailers &# 39 ; job within a mixed mailer mail stream . this is preferably accomplished in real - time or near real - time while sorting the mail pieces after the mailers &# 39 ; specific mail piece characteristics have been determined .