Manning runs a number of different systems and recently moved the university's 3000 staff over to Symantec's BrightMail and has seen big improvements.

Previously, the university just ran a heuristic engine, but spam got worse and manual keyword updates were required.

Vinidex & MM Electrical Merchandising IT manager, Trevor Batten, said the spam problem escalated about 12 months ago accounting for 20 percent of all e-mails at the company. With 1600 users, Batten said using a managed service was the most economical solution.

He said Verizon Business (formerly MCI) came on board 10 months ago and it is almost 100 percent effective.

Kevin Salter, head of IT support at Brisbane-based accounting firm Moore Stephens, said that over a single weekend the company's filtering software picks up about 2500 unsolicited e-mails. But as a Clearswift MIMEsweeper user, Salter said the problem is manageable.