Delivery time for first-class mail in the United States is typically 1-3 business days. First-class mail is the quickest and most economical way to send letters, cards and lightweight merchandise.
A first-class letter can weigh up to 13 ounces.There are maximum limits for the length, height and thickness of flat envelopes.
The 2014 price of a Forever stamp for first-class mail is 49 cents, per ounce. Services, which can be combined with first-class mail to confirm its delivery, are available for an additional price. Lightweight merchandise sent through first-class mail comes with insurance for up to $5,000 for damage or loss.