A new report by DoubleClick finds that some e-mail marketing metrics, like delivery rate, hit all time highs in the fourth quarter of 2004, while others declined.

Delivery rates have gradually increased since 2002, while open rates have declined and click-through rates have wavered but generally held steady. At the end of 2004, delivery rates stood at 90.6%, up from 87.3% at the end of 2003. Open rates were down from 36.8% in 2003 to 32.6% in 2004. Click-through rates declined slightly, falling from 8.4% at the end of 2003 to 8.0% at year-end 2004.

A glance at open rates would give the impression that users are opening a lot less e-mails than they did one year ago. But DoubleClick feels that the reason for the decline is less about a change in the number of clicks than the effect of image blocking technology used by many e-mail programs. Since DoubleClick measures open rates by tracking image calls in HTML-formatted e-mails, image blocking obviously affects this metric.

However, the lowered rates may in fact be more representative of the truth, according to DoubleClick. Before image blocking, many e-mails may have registered as "opened" when they had merely shown up in an e-mail preview window as a user scrolled through e-mails or clicked on them before deleting. The relative stability of click and conversion rates supports this view.

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