DoubleClick's sixth annual Consumer Email Study points to a confluence of personal and professional email use, a decline in concern regarding spam along with an increase in anxiety regarding viruses and fraud, and confirmation that email drives commerce both online and in stores. Though 57 percent of survey respondents view work email at work at least occasionally, nearly as many check work email from home, at night (55 percent) and on weekends (54 percent). Also, 48 percent check their personal emails at least occasionally at work.

Some 74 percent point to brand - "a brand I know and trust" - as the element most likely to drive a response to an email.

Some 78 percent have made a purchase as a result of an email; 59 percent have redeemed an email coupon in a store; and nearly one-third have clicked on an email and made an immediate purchase. Moreover, one-third say they have clicked on emails for information and returned later to make purchases.

Nearly half of respondents report owning at least three email accounts, but 95 percent consider one of those addresses to be a primary account and 72 percent use a single address to make purchases online. On average, consumers maintain an email address 4-6 years.

Though spam still concerns most email users (55 percent are very concerned), viruses (75 percent), identity theft (67 percent), spyware (66 percent) and scams (61 percent) are greater concerns. Nearly half check bulk mail folders, and more than 40 percent report finding legitimate emails there.