37 CFR §1.54

1. (a)It is desirable that all parts of the complete application be deposited in the Office together; otherwise, a letter must accompany each part, accurately and clearly connecting it with the other parts of the application. See § 1.53 (f) and (g) with regard to completion of an application.
2. (b)Applicant will be informed of the application number and filing date by a filing receipt, unless the application is an application filed under § 1.53(d). A letter limited to a request for a filing receipt may be signed by a juristic applicant or patent owner.