The price to mail a letter is going up unless you have Forever stamps. Photo: Paul Ratje/AFP via Getty Images
The cost of postage stamps is going up by 3 cents on Sunday, the third price hike in the last 12 months.
Why it matters: It's the 17th rate change since 2000 and the shortest time between stamp increases in the Postal Service's history.
• Rates last went up in…