Among the first companies to be approved by the U.S. Postal Service to sell postage online, Stamps.com has more than 735,000 monthly subscribers and printed $1.6 billion in postage during its second quarter ended in June, up 6% year over year, while recording revenue of $139.6 million, up 20% in the same period. The Los Angeles-area company just completed its acquisition of U.K.-based software company MetaPack, which counts Adidas, Urban Outfitters, Zulily, and The North Face among its customers. The acquisition will allow Stamps.com to expand internationally and bring an immediate “tenfold increase” in the number of carriers it can support, CEO Ken McBride said on the company’s second-quarter earnings call.