(March 15, 2019, 10:43 AM EDT) -- LOS ANGELES — An investor on March 13 filed a securities class action lawsuit in California federal court against an online provider of mailing and shipping solutions and certain of its executive officers, alleging that the defendants misrepresented the company’s financial results and relationship with the U.S. Postal Service (USPS) in violation of federal securities laws (Matt Karinski v. Stamps.com Inc., et al., No. 19-1828, C.D. Calif.)....