Analysis of more than 500 million junk messages found that addresses that began with an A, M, S, R or P were likely to receive 40 per cent of their mail from spammers.

The analysis was carried out by University of Cambridge computer scientist Dr Richard Clayton, in a bid to understand the widely noted discrepancies in the amounts of junk mail or spam that different people receive.

Dr Clayton took as his dataset the 550 million e-mail messages sent to customers of net service Demon between 1 February and 27 March 2008.

Commenting on the research at a spam and email conference in California, Dr Clayton said, “Measuring incoming email has shown that the first letter of email addresses makes a difference to the proportion of incoming spam.”