On the top floor of the Attic, a streetwear shop in Buena Park, Calif., Derek Rhie punches away on a computer, and then with one click, sends the memo via text, instant message and e-mail. In mere seconds, the room fills with bleeps and buzzes, his phone vibrating on his desk as a series of boxes pops up onscreen.

“Already, here’s the IM, the e-mail, and I just got the text,” says Rhie, as he flips open his phone. “It’s immediate.”

But this is just a test. After all, Rhie doesn’t spend his days sending messages to himself. Instead, he blasts them to thousands.

Sitting at his desk, sporting an untucked button-down shirt, shaved head and three-day stubble, it appears that Rhie is exposing the refined and controversial practice of shooting mass electronic mail, but he’s not a spammer. He’s the founder of Trumpia, a company that allows anybody to send time-sensitive texts, IMs and e-mails to large distribution lists. It can be done from a standard computer or cell phone, and software is not required.

“There are companies that do mobile text and e-mail, but we are the only company that also does IM, and integrates all three,” says Rhie, who manages Trumpia out of the Attic office both because he’s helping the owners (they’re friends) develop their online sales and because “working at home is completely depressing.” The Trumpia headquarters are based in Seoul, and Rhie’s father, Ken, is the CEO of the company (as well as Silicon Valley start-up notable and president of Z60 Ventures in Los Altos).

Rhie, 26, studied engineering at UCLA but the department’s lack of the fairer sex was discouraging. “In class, there would be 60 guys and one girl, and that one girl was pretty much a man,” he says. He switched to economics and minored in computer science, and after graduation, worked as a brand manager for Disney Mobile, a now-defunct mobile phone service that catered to families with tweens. In 2005, when News Corp bought MySpace for $580 million, “that validated to me that there’s something in Internet that can make a lot of money,” he says, “and I decided to start a social network.”

The next year, Trumpia was launched as a social networking tool, similar to MySpace or Facebook, but with a “real-time Evite” feature that would allow, say, a fraternity leader to text mass invites for last-minute drinking binges. “But people who were using our services were not the frat leaders, but businesses who wanted to text their customer base,” says Rhie. Others who rely on Trumpia are party promoters, stockbrokers, churches, restaurants, nonprofit organizers, fundraisers, schools and real estate agents.

Most e-mail and IM programs include features for sending group messages, but the task can be tedious and time-consuming, and have limitations on how many contacts can be used for one message. “If you want to send a huge IM blast, you’re not going to sit down on your computer and add 5,000 buddies to do so,” says Rhie. “The same goes for e-mail. Logging thousands of contacts takes forever, and if [an alert] is coming from a personal Yahoo account, it looks unprofessional.”