Two post offices in West Marin may reduce operating hours as hundreds of other small-town locations in the Bay Area and around Sacramento face similar cutbacks to continue operating with limited finances. U.S. Postal Service officials this week sought public input to alternatives presented at a meeting in San Geronimo to shuttering a mail system that, as of spring, was among thousands across the country limping toward closures, Augustine Ruiz, a regional spokesperson, said. Reducing daily office hours from eight to six were among four alternatives proposed by postal service officials. Others include moving operations into a local business, joining a nearby mail system or offering only roadside delivery. A meeting scheduled tonight at the Dillon Beach post office will notify residents of similar plans meant to reduce operating expenses. The U.S. Postal Service had planned to close about 3,700 offices in rural communities across the country, a decision Mr. Ruiz attributed to the national recession and a dwindling customer base of corporations and businesses whose transactions now are done online. That drop in the past six years has resulted in a 25 percent loss of volume, or 43 billion pieces of mail, Mr. Ruiz said. “It’s never going to come back,” he said, referring to the national carrier’s customer base. “When you lost this much volume, revenue goes with it.” But after reviewing surveys distributed by the U.S. Postal Service that showed peaks of revenue at certain post offices mainly come during afternoon hours, officials agreed to seek public input to consider whether to keep 13,000 offices operating under a tightened schedule, Mr. Ruiz said. Reducing operation times is necessary for the U.S. Postal Service to compete with private businesses whose sales of mail items like stamps and envelopes have partly caused the service to lose more than 40 percent of its retail sales. Though rural locations are facing cutbacks, the shipping industry is “very vibrant,” Mr. Ruiz noted. “So far,” he said, “nobody has figured out how to email a sweater.”