The company will pay a maximum of 20m pounds ($36.9m) plus the assumption of 1.2m pounds ($2.2m) of short-term debt for the Reading, UK-based email security outsourcing business.

BlackSpider has picked up approximately $10.5m in venture funding to date, principally from Cazenove Private Equity, and trades chiefly out of the UK, but has offices in France and Germany, and data centers in Europe and the US.

Patricia Sueltz, the CEO brought in from Sun Microsystems last year to turn the SurfControl web-filtering business around, said in February that she had plans to make further investments in infrastructure and people in the second half of 2006. This acquisition also means SurfControl could start to follow some of its competitors and deliver to market layered security options in the three form factors of software, hardware appliance, or managed service.

Rivals like Symantec and Websense have been making noises that their customers are asking for options in deployment method because they want to shape the feature set and flexibility of their safeguards as it impacts on the cost of ownership of the security infrastructure.

The hosted market that BlackSpider is in has seen rapid growth over the last couple of years, with young firms such as Postini, MessageLabs, and FrontBridge already serving thousands of mid-size companies.

In its last audited numbers for the year ended June 2005, BlackSpider recorded revenues of 1.8m pounds ($3.3m) and a loss of 3.1m pounds ($5.7m). According to Harnish Patel, SVP EMEA for SurfControl, to the end of June 2006 the business had un-audited revenues of 4.0m pounds ($7.3m) and should post a pre-tax loss of 3.3m pounds ($6m), mostly on the back of infrastructure investments and office expansion.

He said the purchase will see the addition of 1,200 customers of BlackSpider’s on-demand MailControl and WebDefence services to SurfControl’s own 22,000 strong customer base.

SurfControl has said that its trading status has progressed well during 2006 and that it expects to post full-year revenue and profit in line with its previous guidance. It expects the BlackSpider transaction to start to generate a positive contribution to operating cash flow and pro forma profit during the fourth quarter of 2007.