Want your marketing message to be at the top of the heap when potential customers check their e-mail? Send it after midnight. According to recent newsletters from eMarketer ( www.emarketer.com), a study by AOL and Opinion Research Corp. shows that 41% of Americans check e-mail first thing in the morning, but 40% have checked their e-mail in the middle of the night. After dinner is the favorite time for 18% of those surveyed, 14% check e-mail when they get home from work, and 14% log on right before bed.

And don't worry about missing people because they're on vacation. According to a Travelocity survey, also reported in eMarketer, more than half of all consumers check personal e-mail while on vacation, even if they're traveling. Leading the pack at 77% are young vacationers (ages 22 to 34), followed by 64% of early Gen Xers (ages 35 to 45). Boomers (ages 46 to 59), at 58%, were edged out by old-timers, who check their e-mail at a rate of 60%.