BT monitored more than 25 million emails sent by its customers over a two-week period in March. It found nearly 11 million (41 percent) of the messages were junk mail.
More than four million spamming incidents were identified on Thursday, making it the most popular day of the week for distributing unsolicited emails.
"The problem with spam is well documented, but to get close to the 50 percent mark is astonishing — and the figure can only increase. The best option users have is to protect themselves. That way they can continue to use email as an effective communication tool without being subjected to the irritation and hindrances that spam brings," said Duncan Ingram, managing director at BT Openworld.
Junk email seems to be at the top of government and industry hitlists right now. Microsoft's recent spam-fighting partnership announcement, AOL's tough stance with its AOL 8.0 software package and Labour's plans to enforce EU rules that will make unsolicited mail illegal, have all pushed the issue to the fore recently.
"I can't think that it helps anyone in any activity to have their computer flooded with some of this quite distasteful material," said science minister Lord Sainsbury, speaking at a recent anti-spam event.
The Federal Trade Commission called an emergency meeting on Sunday to discuss the problem. The convention closed with the Commission calling for immediate action, although what this action would be was uncertain.
It seems the only way to tackle spam is to present a united front, but the chances of governments penning a global strategy is slim to none, leaving the end user no choice but to take measures to protect themselves.