Email marketers must primarily rely on the relevance of their promotional messages to increase conversions in the face of competition from social media.

This is the conclusion of a new report published by JupiterResearch, which showed that the rising popularity of social networking websites and applications has led to lower email marketing success rates.

JupiterResearch said that while 51 per cent of consumers purchased at least one product or service as a direct result of an email message last year, this has fallen to 44 per cent in 2008.

The company also revealed that 22 per cent of email users now make use of social networking to communicate with others rather than email.

"People receive such a high volume of email that they are unable to pay attention to every message," said David Daniels of Jupiter Research.

"It is so important for marketers to be relevant and succinct when they send messages to consumers' inboxes."

A recent study by Gartner found that internet users are becoming increasingly attracted by the social aspects of communication as opposed to "transactional, diverting or functional" elements.