You can set the time back as early as the beginning of the current day, and you can advance the time up to 24 hours (which means you are in the next day).
To adjust the time:
- From the Home screen, select Mail.
- Select Options from the list on the left.
- Select the date:
- Select Set to Todays Date. You return to the Mail screen with today's date set.
- Select Advance the Date, then either Add one day or Enter days to add (1-30) to advance more than one day.
UPDATED: October 31, 2016