Self & Rubber Stamp Rubber stamps for business commonly show an address, corporate logo and business registration number.[5][6] Some stamps also have movable parts that allow the user to adjust the date or the wording of the stamp. They are used to date incoming mail, as well as to denote special handling for documents. In some countries it is common practice for formal documents such as contracts to be rubber-stamped[7] over the signature as additional evidence of authenticity. The objective is to authenticate the contracts, prevent forging, and increases efficiency as company executives do not have to separately sign individual company documents.