In this increasingly mobile world, hotels have become an essential channel of communication for important messages. Past campaigns have alerted guests to the millions of gallons of water used in washing towels and educated travelers about the signs of human trafficking and the steps to take in the event they observe suspicious behavior.

Now Maria Shriver’s A Woman’s Nation and Marriott International have teamed up to shine a light on hotel housekeepers, the under-compensated, silent majority of the hospitality labor force. Timed to coincide with International Housekeepers Week, “The Envelope Please” is an initiative that encourages hotel guests to express their appreciation for the housekeepers who toil away fluffing pillows and scrubbing toilets while largely remaining invisible to guests but for brief encounters in hotel corridors, carts in tow.

As of Sept. 15, upon checking into their rooms, visitors to 160,000 Marriott hotels in the U.S. and Canada will discover notecards and envelopes that gently encourage—and enable—them to write notes of thanks and provide gratuities to the keepers of their homes-away-from-home. Shriver hopes to expand the program to other Marriott franchises as well as to non-Marriott hotel chains.

Read more about “The Envelope Please.”