Kourtney Kardashian, Travis Barker Kiss in Matching Mr. and Mrs. Jackets

Kourtney Kardashian's telegraphing a not-so-subtle reminder to the world she's a Barker now -- and it's written all over her and Travis Barker too ... in case you've been under a rock.

The newlyweds were still in Portofino, Italy Monday night, and rocked matching white leather jackets -- one embroidered with "Mrs. Barker" on the back, and the other with "Mr. Barker."

As we've told you, Kourtney was quick to take Travis' last name on Instagram ... changing her profile Monday evening to Kourtney Kardashian Barker.

One thing that hasn't changed is their penchant for serious PDA!!! Trav and Kourt were still all over each other during their evening outing -- just a day after saying their "I Dos" before family and friends.

Their over-the-top wedding -- their 3rd one -- was held at the stupidly scenic seaside compound of Domenico Dolce and Stefano Gabbana.

While we don't know if Kourtney's planning to legally take Travis' name, the jackets and IG change are strong hints she will do exactly that -- if they ever come back from Italy.