Outlook uses the long date format set in Windows for date formatting in the calendar, both onscreen and in printouts. For example, if you want to include the day of the week on printed calendars or display the full name of the month above the navigation calendars, check your long date format in Control Panel’s Region and Language applet.
You can make your own date formats if you don’t care for any of the defaults – open the Region and Language applet and click Additional Settings, then the Date tab. Type the new format in the field, using d or dd for date, ddd or dddd for day of the week, M, MM, MMM, or MMMM for month and yy or yyyy for year. You can use period, space, comma, slash or dash for separators (possibly other characters).
Note: the date format used for sent & received fields in the message list is set in Format Columns. Right click on the row of field names and choose Format Columns – if its not an option, choose Custom (older versions) or View settings (Outlook 2010).
Published February 2, 2011. Last updated on July 27, 2012.