Make a letter in writing. A single sample for such a message does not exist, therefore, it should be guided by General rules adopted for business correspondence. In accordance with the introductory part reserved for the details. If your organization has letterhead, then it is best to print the letter on it. In addition, you won't have to collect your own details and will be sufficient to specify the destination format. Specify here the position of head of the firm-partner, corporate name, name.
Start the cover letter with the words "send you". You can pre-specify the essence of the appeal "On the shipment documentation, but it is not a requirement, as was the need to title the document. Let the reasons for the transfer (in the framework of the contract, on request, by prior agreement, etc.). List all documents in the section "Application". If more than one, it is best to draw a table, which will contain a sequence number, name, number of sheets, copies, etc.
In the final part of the treatment please tell your partner your wishes. This may be a request for return of documents, to inform about the receipt etc. Then leave a space for signature of head of your organization, specify its position and interpret in parentheses the name. And then inform the surname, name, patronymic of the contractor and his contact number for reference.