Ben Fox Rubin/CNET

Amazon's giant celebration of itself, Prime Day, is expected to be July 15, according to a report of a leaked public relations email.

The event is always one of the e-commerce giant's biggest times for sales -- and it also offers consumers some of the company's deepest discounts of the year.

The dates for Prime Day, which may actually stretch from July 15 through July 17, were first reported by website Real Homes, based on a PR email the publication received promoting a vacuum cleaner deal.

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In what will be its fifth year, Prime Day has become a buzzy sales event the e-commerce giant can use to pump up revenue during the typically slow summer season. Amazon repeatedly breaks its single-day sales records on Prime Day -- though for the fast-growing retailer that record is typically bested yet again on Black Friday or Cyber Monday later in the year.

The discount event is also a method to entice people to join Prime, Amazon's membership program best known for fast, free shipping.

Last year, the e-commerce holiday had a rough start. A series of glitches took down the app and the website, but Prime Day recovered and sales were strong.

Originally published June 5 at 7:54 a.m. PT.

Update at 8:19 a.m. PT: Adds background details.