E-mail customer service was worse in 2005 compared with previous years, according to a JupiterResearch study released in March.

Jupiter sent test inquiries to 255 U.S. businesses with websites, 234 of which offer customer support by e-mail. Twenty-five percent of the companies answered the e-mail questions within six hours. But fewer companies met the six-hour mark compared with previous years: In 2004, 28 percent of companies answered within six hours, and in 2003, 27 percent did.

In the 2005 study, 20 percent of the companies responded between six and 24 hours. At the bottom of the scale, 39 percent of companies took three or more days to reply or never responded at all—more companies than in previous years.

“Those that are answering e-mails on average are doing better, but unresponsiveness continues to rise,” says Jupiter associate analyst Zachary McGeary.

Slow or nonexistent e-mail replies negatively affect a company’s revenue and can increase a company’s expenses as well as hamper e-commerce, he says. For example, after a poor customer service e-mail experience, consumers might sour on the company and be less inclined to buy its products online and offline. They might also tell acquaintances about the subpar treatment.

Snubbed online shoppers are also likely to attempt to contact the company via phone, adding to customer service costs, McGeary says.

Jupiter’s research indicates that consumer e-mail questions will increase in coming years, with the overall volume expected to increase 23 percent from 2005 to 2006, and an average of 18 percent a year between 2006 and 2010.

Fewer than half of polled sites acknowledged consumer questions with an automated response, although some industries, such as music, retail and travel, fared better in this category. Financial companies were least likely to send acknowledgements.

Failing to acknowledge an e-mail with an automated response violates consumers’ online service expectations, says McGeary. For example, he adds, “You don’t expect receipts from e-mail with friends or family, but you do with retailers because online purchasing requires buyers to place sensitive information, like credit card numbers, on the Web.”