Messaging software is set for healthy growth but vendors still have a lot of work ahead of them to deal with the number one customer anxiety - security.

This is the conclusion of the The Radicati Group's new study, "Messaging Software Market, 2004-2008", which sees average annual growth rates of 8 percent over the next three years.

Despite its popularity, the sudden rise of spam volumes, phishing scams and e-mail-based Trojans and worms in 2004 have turned messaging and e-mail into a critical security issue for companies.

In 2004, total messaging volume grew by 35 percent to a claimed 76.8 billion messages per day, of which 83 percent were to or from corporates or large organisations. Spam now accounts for 49 percent of this traffic, or 38 billion messages per day.

Last year did at least see an upturn in the messaging market after a difficult 2003, with the global number of e-mail users growing 15 percent to reach 651 million. By 2008, messaging software revenues are projected to reach $3.6 billion from a user base of 1.6 billion mail boxes.

Key growth segments will be smaller and medium-sized companies and the rapid rise in the number of e-mail users in Asia.

IBM Lotus will see a continuing decline in its market share after a poor performance in the last 12 months, leaving Microsoft to control the market. The report summary was non-committal about the prospects for open source and independent email packages but sees this segment of the market making modest inroads into Microsoft's dominance.