Saturdays saw e-mail open rates of 38.3 percent, and click-throughs of 5.4 percent. Open rates also were high on Sundays, at 37.1 percent, while click-throughs reached 5.2 percent for three days--Sunday, Monday, and Thursday. Fridays performed the worst for both open-rates (32.7 percent) and click-throughs (4.4 percent).

Data about click-through and open rates was gleaned from e-mail campaigns that eROI sent during the quarter. Separately, eROI also surveyed 300 e-mail recipients about their e-mail habits and preferences.

Most recipients of business-to-business e-mail--79 percent--said they subscribed using their business address. But a far smaller proportion of consumer-oriented e-mail--57 percent--said they subscribed using personal e-mail addresses, while 24 percent subscribed using an address created for e-mail lists and 19 percent subscribed using their business addresses.

When asked which day they would like to receive e-mail, recipients of business messages chose Monday (33 percent) and Tuesday (36 percent) more than any other day of the week. For personal e-mail, the most popular day was Friday (31 percent), followed by Wednesday (26 percent).

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