Shares of Santa Monica-based online postage vendor Stamps.com Inc. surged 19.1 percent on Tuesday after the company announced its popular PhotoStamps program was set to return to the market.

A test run of the personalized stamp service, which allowed customers to create official U.S. stamps from their own pictures, was halted last September after images of Unabomber Theodore Kaczynski made their way through propriety screeners.

On Tuesday, Stamps.com said it expects PhotoStamps to be available under authorization of the U.S. Postal Service for a year-long market test beginning May 17. It began taking orders immediately.

Monday afternoon, the Business Journal reported that the Postal Service plans to relaunch the personalized stamps program that was run by Stamps.com. While the program will be put out to bid, few vendors are capable of implementing it, said Gerry McKiernan, a Postal Service spokesman.

“My expectation is that (Stamps.com) is standing at the door right now because all they have to do is turn on the switch,” McKiernan said.

The relaunch is the second phase of the Postal Service’s PC Postage program and will last one year, until May 2006. In the few months that the service was available, the program sold 2.7 million stamps a huge success until the muckraking Web site The Smoking gun sent in several infamous photographs, including Kaczynski, Cold War spies Julius and Ethel Rosenberg and presidential whistleblower Linda Tripp.

The images managed to get through Stamps.com’s approval process, and the prank was reported by several news organizations.

Stamps.com shares fell sharply when the program was first suspended on Sept. 30 but had already recovered by this week. On Tuesday, after Stamps.com’s announcement, Stamps.com shares were trading at $19.84 each, up $3.18 on the day.