According to DoubleClick's second-quarter "Email Trend Report," published yesterday, key email performance metrics, including the non-bounce rate, click-to-purchase conversion rate and orders per email delivered, improved compared with 2Q04 - despite the continuing decline of open rates, to which the report devotes a "feature section." The bounce rate was at an all-time low at 7.9 percent, falling 25 percent from 10.5 percent 2Q04, and down 5 percent from the first quarter's 8.3 percent.

But open rates declined for the fifth consecutive quarter, falling to 27.5 percent, compared with 2Q04's 36.0 percent. According to the report, three forces seem to be causing the decreases in open rates.

ISP and email technology changes (especially image blocking), file aging (older email addresses growing in proportion to new ones, which tend to perform better), and evolving consumer behavior (greater selectivity in opening emails) are all at work in pushing down open rates.

Click-through rates remained relatively stable despite the declining open rates. Click-through fell slightly from 7.7 percent to 7.2 percent. The HTML click-to-open ratio increased from 26.5 percent to 32.0 percent.

For retail and catalog marketers that track purchase activity through DoubleClick's DARTmail, the click-to-purchase conversion rate rose to 4.6 percent from 2Q04's 3.6 percent, while orders per email delivered rose 18.2 percent to 0.26 percent versus 0.22 percent a year ago. Average order size declined 14 percent (from $93 to $80), but revenue generated per email remained unchanged at $0.20.

The executive summary of the report and the section on open rates is available at www.doubleclick.net/knowledge.