A method for controlled acceptance mail accounting and evidencing, includes creating a mail batch including at least one mail piece having an encrypted indicia printed thereon. The encrypted indicia is generated by the use of a key K.sub.m. A statement of mailing file is created containing data related to the mail batch. The statement of mailing file including the key K.sub.m is encrypted with a public key of an authentication unit of a carrier distribution system. The public key has an associated private key. The mail batch and the statement of mailing file is submitted to the carrier distribution system and the mail batch and the mail documentation file is processed using the private key of the authentication unit of the carrier distribution system to decrypt the encrypted information and recover the K.sub.m. The key K.sub.m is then used in an authentication procedure related to the mail batch. The statement of mailing file may be sent in tangible form or in electronic form to the carrier distribution system. A plurality of public keys of a plurality of authentication units may be available for encryption of the statement of mailing file including the key K.sub.m. The encryption process may be implemented separately with different public keys of different authentication units when it is not yet determined which authentication unit will perform the processing. This provides greater flexibility in the selection of the authentication unit to process the mail and achieve systems efficiency.