THANK HEAVEN THAT summer is over and we can all get back to work. I can't tell you how dull my mail was in July and August; my mailman yawned as he handed it in the door. But now that it's September, things are picking up, and as the fall publishing hype begins, the bulging envelopes and press kits once again yield up chuckles. Witness: in order to promote its paperback original series of westerns, the Longarm books, Jove has hired itself a real live cowboy, one Bruce Kurland, to impersonate the sexy Longarm on a publicity tour. The Longarm series is the macho equivalent of those passionate historicals that ladies are munching like peanuts; the titular character spends as much time in the bedroom as he does gunning down the guys in the black hats. So, for two months, the lucky young women of Jove's publicity department have been interviewing actors and models-- 100, count them, 100-- for the coveted role of Longarm. They have not been very specific with me about exactly how the interviews were conducted, or what talents the potential Longarms were asked to display, but they agree that Kurland, the winner, is sensational. Kurland, an actor and model, is from Boston. "Bruce's smile is captivating," purrs Jove publicity, "his eyes hold a woman and pull her toward him, his movements are fluid. In essence, we have found Longarm complete with all the sensuality the character exudes in the books." Can he ride? we asked. "Oh, yes, he will ride a horse on the entire publicity tour." Can he rope? Can he shoot? "Well . . . we did rent him a Colt .44-40, but it's only a prop." Can he . . . ? "He's Jewish," interrupted Jove with a giggle. Jewish? JEWISH? "Mmmmmm," purred Jove.

A Jewish cowboy? I don't know why I find the entire thing so absurd; maybe it's because, in the Washington Heights shtetl where I grew up, all the boys wanted to be rocket scientists or the president of Princeton University. Nobody ever said anything about wanting to be a cowboy, even a rented one. Listen, Bruce pardner, I wish you mazel, but be careful with that gun, you hear? THE RIALTO

PERIGORD PRESS, THE TENUOUS entity formed by William Morrow and Bantam Books and named for the restaurant where the discussions took place, is tenuous no longer. They have signed up their first book, an "untitled work of fiction" by Gerald Green, for a sum in the "high six figures." I called Jack Scovil at the Scott Meredith literary agency to find out what the new novel would be about. "Nobody knows," confessed Jack. "Even Gerry has no idea, yet." How come? "Well, he's just turned in a completed novel to Playboy Press, on an old contract. It's called The Chains, and it's the story of a Jewish Mafia family. So he's been busy with that." As you may remember, the purpose of Perigord was to lure to it big-name, best-selling authors by presenting them with joint (therefore larger) advances from Morrow (hardcover) and Bantam (paperback) and arranging for them to keep 100 percent of their royalties. Green, who attained fame as the author of The Last Angry Man, certainly fits into that blue-chip category. His Bantam original paperback, Holocaust, the tie-in with the highly successful television series he penned, has nearly 2 million copies in print; translation rights have been sold worldwide to 18 foreign publishers. Green is also the recipient of the 1979 Prix International Dag Hammarskjold Award.

While we're on the subject of Bantam Books, some important changes in responsibility have occured very lately. Marc Jaffe, who was president and editor in chief of the company, is relinquishing all editorial duties to become president and publisher of Bantam, assuming total publishing responsibilities. Rollene W. Saal, who left the Literary Guild (where she was editor in chief as well as vice-president and editorial director of the Doubleday Book Club division) to join Bantam Books last May as vice-president and editorial director of adult general fiction and nonfiction, now takes up the editor-in-chief's chair and title, with all editorial personnel and editorial operations reporting to her, although she will be reporting to Jaffe, who will supervise editorial policy. Oscar Dystel is, of course, still chairman of the board and chief executive officer of Bantam. But it seems to this viewer that Oscar's retirement is near and that the duties that Jaffe is assuming go towards making that regrettable transition happen more smoothly. Few men in this industry are as respected as Dystel, not only for his business acumen and intelligent guidance, but for the warmth of his personality and his regard for people's feelings. Bantam is one house that has never, in my recollection, been "troubled," although there were fireworks not long after its founding more than 30 years ago. People spend lifetimes there. The family feeling and communality of spirit are so strong that they're sometimes joked about in the business. Yet, I believe that a great part of the family feeling is due to Oscar Dystel's care to see that talent and hard work are rewarded, and there are more vice-presidents per square foot at Bantam than at any other house I know.

And speaking of longevity, Image Books will be 25 years old next month. It was the first line of trade religious paperbacks (Catholic) offered on the general market by a trade publisher (Doubleday), designed to make them available at the lowest possible cost. Since its founding in 1954, Image has published 420 books with an aggregate total of 22 million copies in print. Its all time number-one best seller has been, predictable, The New Testament of the Jerusalem Bible, with 815,000 copies, but it has also done extremely well with Parents, Children, and the Facts of Life, 727,000 copies. Its best-selling multi-volume work, Frederick Copleston's The History of Philosophy (nine parts, 17 volumes) has collectively sold 1.6 million copies to date. Doubleday Image has broadened its criteria for selection over the years to meet changing times, including the ecumenism following Vatican II. Their authors range from Saint John of the Cross to Pope John XXIII, and now include biography and fiction as well as theology, mysticism and scripture. Happy birthday, Image. TODDLING TOWN

"Things must be a little slow in Chicago," remarked William Sarnoff dryly. The chairman of the board of Warner Books was referring to the banning by the Chicago Transit Authority of the bus card advertisements for Frank de Felitta's The Entity. What is overheating the CTA's engine apparently, is the word "psycho-sexual" in the ad copy on the transit poster which reads, "the most shocking psycho-sexual thriller ever published." "More seriously," Sarnoff adds, "we are against censorship in all its forms," but behind his words do we detect a light note of glee? After all, when Gael Greene's Blue Skies, No Candy was rapped by the MTA in New York for its "lewd" cover, Warner sold a whole buncha copies. Does Sarnoff think sales for The Entity might be boosted in Chicago? "I shouldn't be surprised." These liberal days, when it's soooo hard to get banned in Boston, one is grateful for anything one gets, even for a Chicago bus company.