"Although Apple and FedEx tracking information may currently indicate a later date, you can check the FedEx website the morning of the June 23 to track your package to your doorstep," reads the text of the Apple e-mail.

Apple has scheduled the iPhone 4 delivery date for June 24, but the e-mail from the company confirms the first delivery date as June 23. Apple advises those who cannot accept delivery on June 23 to use the pre-signed delivery option.

This is an unusual move for Apple, as the company usually held back deliveries until a set date, despite the goods being in FedEx custody a few days earlier than the delivery date. In the case of the iPhone 3GS, and more recently the iPad, FedEx stuck to the initial Apple-set delivery dates.

Apple said last week it saw record numbers of iPhone 4 pre-orders in the first couple of days of availability, as many as 600,000, but . Problems plagued AT&T's servers, which in turn took down Apple's pre-ordering site, leading to queues at brick-and-mortar stores.

Apple had to for the iPhone 4 pre-ordering mayhem, so the move to send the first batch of pre-orders one day early could be aimed at regaining customer satisfaction. Spreading iPhone 4 deliveries over two days would also help to ease the load on AT&T's activation servers, as well as putting less stress on FedEx's delivery schedule.