It was an era when tough guys were able to sell cigarettes on TV... Enjoy.
"Paul Mall" was the sponsor of "M Squad," a television program which ran on NBC during the '50s. That's perhaps why Lee Marvin, the show's star, appeared on its commercials during the episodes.
As for his quirky pronunciation? The cigarette's name is correctly pronounced with the rhyming couplet "pell mell," as made evident in the advertisement.
The American Tobacco company would dispatch numerous publicists to instruct the cast and staff of the correct pronunciation during live commercials. With the dissipation of cigarette advertising, first with bans on radio, then television, the pronunciation has found a decidedly generational tone. Those who lived in the era of the audible advertisements pronounce it "pell mell" while those of us -- MOST of us -- have only the visual title of the packaging to refer to often use the increasingly more common phonetic "paul mall."