DoubleClick's quarterly Email Trend Report of email marketing performance showed that Q1 2005 revealed open rates dropped by a fifth to 30.2 percent, down from 38.2 percent. That said, click rates remained relatively stable at 7.9 percent, down from 8.4 percent.

DoubleClick attributed much of the open rate decline to a technical issue - where the mechanisms for tracking opens (determining whether or not an image has been retrieved from a server) have been thwarted by email systems that filter out graphics.

Bounce rates seem to be declining across the board, reduced by a quarter from the same period last year, hitting an all-time low of 8.3 percent.