How are electronically filed submissions dated by the USPTO?

The USPTO has specific rules for dating electronically filed submissions. According to 37 CFR 1.6(a)(4):

Correspondence may be submitted using the Office electronic filing system only in accordance with the Office electronic filing system requirements. Correspondence submitted to the Office by way of the Office electronic filing system will be accorded a receipt date, which is the date the correspondence is received at the correspondence address for the Office set forth in § 1.1 when it was officially submitted.

The MPEP further clarifies: Similarly, correspondence submitted via the USPTO electronic filing system (EFS-Web) will be accorded a receipt date on the date the correspondence is received at the correspondence address for the Office set forth in 37 CFR 1.1 (i.e., local time in Alexandria, VA), without regard to whether that date is a Saturday, Sunday, or Federal holiday within the District of Columbia.