Recipients will be invited to click through to a microsite created for the promotion (www.mullerice.com), where they can play a game and enter a competition to win one of five white-water rafting afternoons.
The campaign was created and produced by interactive marketing firm Creative Intellect.
Ben Ahluwalia, chief executive at Creative Intellect, said: "We came up with a fun online game that follows on from the successful Mullerice TV ad.
"Our game emulates a slot machine, complete with a one-armed bandit. It introduces our new fictional characters - Mandy Muller and Rick Rice."
The campaign kicks off the company's marketing campaign to promote Mullerice's redesigned packaging and four new flavours.