The number of lists on the market in 2004 was down 8.1% on 2003, while the number of new lists was down by 33%.
According to the researchers, all list buyers are nowadays demanding data that has been collected or revalidated in the last 12 months, and there has been a natural dip in the demand for lists that fall below accepted high-quality standards in terms of recency, accuracy and selectability.
Three sectors particularly badly hit were photography and video, down 50%, and motoring, down 48.3%.
The researchers ventured that these declines were due to consumer resistance to revealing personal information on guarantee cards for electrical equipment and "trigger" or time-sensitive information such as car re-purchase intention dates.
New email lists were very scarce, with their number dropping 84% from 2003 to 2004. However, the number of email lists available still increased by 4.7%.
Lloyd James Group managing director Lynn Stevens said that it was arguable that the email data market is reaching saturation point.
"It may be that there is a natural cap on the number of people who are willing to opt in to receive email marketing offers," she said.
However, coverage of people over 50 has soared. A bulge in the number of people in the over-50s age bracket brought a 67% increase in the number of lists covering this demographic. The number of new lists grew by 200%.
Stevens said: "Over the last couple of years, marketers have started to realise just how lucrative this market is and there has been much research and discussion around the necessity of moving away from lumping this important demographic into one homogenous mass of older people."
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