Jean-Gabriel Domergue's (4 March 1889 – 16 November 1962) signature is difficult to see in this Salon de Paris postcard, but it's in the bottom left corner of the gondola.
The fine print verso does not specify what year Domergue exhibited this painting, "The Hour of the Serenade," but my online research came up with 1919. And the following year in 1920, he came to the US, participating in The Pittsburgh International Exhibition of Contemporary Painting, and exhibited it here. The white border on the left shows stains. No creases. Looking at the card in hand, the art itself is in near mint condition. If you use a jeweler's loupe and start examining it, you'll see some hints of the text verso have lightly bled through around her collar. This postcard is about 5.5 by 3.5 inches. For someone who was so prolific, postcards of his work are hard to come by. This is the second one I've gotten my hands on, and this one is extra special, in my opinion, because it's one of his earliest ones before he developed his 'pin-up girl' style. (See below). Also, this card has the added interest of apparently having been 'recycled' in the 1930s! As you can see verso, it was used by a gassed war veterans group to advertise about an upcoming lottery drawing! I can't understand everything, but the gist I get is that this card was encouraging members to support certain businesses. "Reserve your purchases to the merchants who deliver to you our participation cards."
Domergue was a French painter, born in Bordeaux, specializing in portraits of Parisian women. He exhibited works at the Salon Des Artistes Français in 1906 at the age of seventeen! He won prizes and gold medals for his landscapes, but his career took a decisive turn during the 1920s when he claims he invented the Pin-Up and he became the painter of the "Parisian lady." He went on to paint approximately 3,000 portraits: nudes and fashion "coquettes," sometimes accompanied by men. He also designed clothes for the couturier Paul Poiret. From 1955 until 1962 he was the curator of the Musée Jacquemart-André (a place I always recommend to anyone going to Paris. It's a mansion owned by art collectors and donated to France upon their death; it's an intimate and elegant art experience!) One of his oil paintings of a red-headed coquette sold for $4500 in 2011. The owner of the Gallery Souzy in Paris has an impressive web site dedicated to Domergue and his paintings that they have sold.