CDMS commissioned research among 2,000 British consumers asking them what factors were most likely to make them open a piece of direct mail, respond to it and make a purchase.
The research found three key factors: the ability to respond online, timeliness of correspondence and personalisation of communications.
CDMS said that the element of conversion to sale was critical if the study was to make the distinction between sheer response volumes and those leading to sales.
The findings show that being able to respond online is 20% more conducive than average to response and purchase, while telephone response rated 16% less likely.
Timing of the campaign to reach the recipient when considering a purchase was voted 17% more likely than average to drive consumers to respond and purchase, while personalisation was also high in importance at 14% more likely than average.
Richard Higginbotham, head of marketing at CDMS, said: "The ability to respond online is now the clear priority amongst UK consumers. According to figures from the Office of National Statistics 65% of UK households now have a home internet connection, and 56% of the nation's households have a broadband connection.
"Although growth in home internet access has been relatively slow in the last three years, it would appear that for direct marketing response purposes, we have crossed a watershed where - assuming timing and targeting have been properly executed, the real differentiator is the ability to respond online."
Higginbotham added that making use of internet technologies allows marketers to link offline identity, attributes and relationships with online visitor details and behaviour.
One example he cited is the use of personalised URLs, which allow marketers to create a personalised landing page for every client in their marketing database.
When the direct mail recipients click on the URL they are directed to their own microsite containing the offers, products and services especially meant for them. Details of who accessed the site and how they behaved can then be tracked.