7:30 a.m. to 10 a.m.The U.S. Postal Service may have more than 700,000 employees, yet there never seems to be enough of them when you're waiting in line to mail a birthday present. Your best chance, according to USPS spokesperson Monica Suraci: Find out when your post office opens (generally between 7 a.m. and 9 a.m.) and arrive a half hour or so later. You'll hit a midmorning lull, missing the rush of early birds lined up at the door (as well as distracted window personnel chatting with carriers sorting the day's mail). Heavy traffic is more likely at lunch, at the end of the workday, and just before closing, so those are times to avoid. Suraci's tip: Look for USPS "contract stations," which offer services in locations like supermarkets and drugstores, and for machines in some post-office lobbies that weigh and stamp packages most any time.