Heavens Union, a California firm, sends messages to the dead.

Dead relatives, dead celebrities, anyone you want, according to Heavens Union founder Gabe Gabor, who has a stable of terminally ill messengers to get the mail through to the hereafter.

Although he does not send messages to dead pets.

"That would be making a farce of this," says Gabor, who has been sending his own messages to his mother and Nobel laureate author John Steinbeck.

Since December, Gabor has sent "over 500" messages to the dead for his clients. The messengers were four terminally ill people, though three of them carried most of the load, after the first one "departed," as Gabor says, in early January, "with just a few messages."

In his office in Granada Hills, a suburb of Los Angeles, he says, in a light Hungarian accent: "We're a legitimate organization. We're bonded."

A hefty promotional package mailed to clients shows a misty photograph of the bald, bearded, frowning Gabor, who is 35 and signs his name simply "Gabor." He says he got the idea for Heavens Union in 1978 when his mother died. "As fate would have it, six months later one of her closest friends was fighting a simliar battle with cancer. One afternoon, while my daughter and I were visiting her in the hospital she said to me . . . 'I wish your mother would know what a wonderful granddaughter she has.' Instinctively, I replied, 'When you see my mother will you please tell her what a wonderful granddaughter she has, and how much I love her.' With that, we both cried."

Since December, clients have been filling out message blanks decorated with pictures of roses and the words: "Heavens Union--Messages to the Hereafter." Gabor and three employes, not to be confused with the messengers, copy the messages into a computer, and take them to terminal patients selected, Gabor says, by psychologists.

The messengers sign copies to show they've read them. "Reading it once is sufficient," says Gabor. "They don't memorize them." Official instructions for messengers say: "Simply reading or having possession of these messages should enable you to relay the full context when you depart. This is made possible by your spirit entering a perfect medium."

The price tag: $60 for 100 words or $40 for 50 words, unless it's "priority service" in which case it's $100 for 50 words, and $125 for 100 words. The messengers get to have $10 a message paid to anyone they want. The Internal Revenue Service has yet to rule on whether this makes a funeral a deductible business expense. Priority service, lest the layman become alarmed at the possibility of extra-legal dispatching methods, merely means that the message is given to three dying people rather than one.

Unfortunately, entering the "perfect medium" does not enable messengers to handle other languages, so Heavens Union is looking for moribund Hispanics to handle the Spanish traffic, with other languages perhaps to come.

"People send messages wishing happy birthday, or saying how much they miss them, or hoping for eternal peace. A lot of messages have to do with parents," Gabor says. "We've had a number of messages to John F. Kennedy, John Lennon and Rudolph Valentino. Most messages are filled with love. Some messages are somewhat angry. Any message using foul language is returned. And we only accept them as long as they're in good taste."

And no messages to hell. (Hell-a-grams?) "I've had messages to hell but we reject them. Most of them were angry."

For one thing, Gabor is certain that all his messengers are going to heaven. "Heavens Union messengers are fully aware of their situation and have had time to be repentant of past mistakes."

But what if the messenger doesn't believe in the conventional Christian heaven--Christians in this country being accountable for the sort of harps-and-angels motifs we associate with the kingdom in the sky. One messenger--the first to depart, in fact--was Jewish.

"They believe in the spirit . . . I've seen people in Jewish cemeteries standing at graves and talking. They weren't talking to the grass."

Also, says Gabor: "What's nice about heaven, it's open to all people."

But why bother with Heavens Union, when we can avail ourselves of prayer, masses, the lighting of candles and so on while we're here? Indeed, the religious community has been less than friendly to this new competition, Gabor says. He puts it all in perspective. "When man started to build the first airplane it was burned and smashed on the ground by people who said that if God had wanted man to fly He would have given him wings."

Doubters in this case would point out that if God wanted people to talk to the dead, He'd kill them, rather like the ancient Incas, who are said to have dumped their messengers down wells soon after giving them messages to the gods.Nowadays, we have Heavens Union, far more benevolent. Gabor even provides sample messages to those who might find themselves with writer's block.

For instance: "Dear Ed, You were right, Tom and Cindy did get married and Tom went into her father's business . . . as president! Miss you around here buddy. (Signed) The Gang (Minus Tom)."

One sample message to "John" may well be addressed to John Lennon. "Your spirit and desire for peace will live forever in your music," it says, over the signature "Ted Smith, Detroit Fan Club."

The metaphysical implications of Heavens Union are staggering. If we can assume that people in heaven don't know things about their own families, couldn't we assume that there are all kinds of things they want to know about everything else? Like: Did Dick and Liz get back together?

Wouldn't we please poor Aunt Sophie more by sending her plot summaries of "General Hospital"? Why not have the messengers learn to sing the latest hits?

Another possibility is mass-mailings addressed merely to "Occupant." It could be the ultimate combination of dead letters and junk mail.

Sooner or later, too, Heavens Union is bound to hire a joker who'll arrive in heaven and go up to Uncle George and say, "I got an important message for you. Don't forget to pick up the dry cleaning." The temptation to lay guilt trips on those embowered in eternal bliss will be overwhelming. "I should be so lucky to be dead like you," somebody will say. "You smoke three packs a day and eat us out of house and home and what do you get--heaven. Me, I get stuck with a Mastercharge bill and your good-for-nothing brother living in the guest room. And if you can can tear yourself away from the harp, how about telling me where you left the other set of car keys?"

(Gabor does not promise responses, but notes that many people ask the dead to contact them, "and they send more than one message.")

"Hopefully," says Gabor, in the tone of a man who gets asked the same questions over and over, "there's going to be a lot less skepticism."