Post offices in most towns are open weekdays only from 8:30 or 9 to 4:30 or 5.
Within Europe, postcards and airmail letters both need IKr 70 postage. Letter and postcard postage to the United States is IKr 90.
Mail to Iceland from northern Europe and Scandinavia usually takes two to three days; other services are slower. All post offices have fax machines.