"Seinfeld" star Wayne Knight's still got it -- he's unleashing a trademark Newman rant to point the postal finger at the Trump administration for slowing mail service ahead of the election.
Newman threw on his old U.S. Post Office wardrobe for a PSA video dedicated to Friday's World Post Day ... the anniversary of the Universal Postal Union, which started in 1874 in Switzerland.
Check out the video ... Newman wastes no time, hilariously digging into President Trump, his Postmaster General Louis DeJoy and what looks like a giant turkey leg.
It's classic Newman laughs, but he does take serious shots at POTUS, accusing him of attempting to kneecap the post office by slashing employee hours and removing mailboxes.
From the second Wayne opens with, "Hello zip codes. And, you plus-fours, you know who you are" ... ya just know it's gonna be funny.
He might have saved his best shot for DeJoy, saying ... "That guys' never even licked a stamp."
The PSA, spearheaded by an anti-Trump super PAC, comes on the heels of "Cheers" star John Ratzenberger also suiting up in his old post office uni to rally behind the U.S. Post Office.
Not all heroes wear capes.