Avinti on Wednesday announced a new version of its e-mail security software designed to catch inbound messages with active content and embedded URLs that can expose recipients to Internet threats.

Slated for availability in June, Avinti’s iSolation Server 4.0 extends the company’s Observation Engine, which catches inbound threats by flagging messages potentially containing a virus or malware and running them through the engine that executes code in a safe, contained environment at the gateway, according to company officials. If the code attempts to do something abnormal, such as modify the system registry or access an Outlook address book and scan e-mail addresses, the message will be flagged accordingly.

With this upgrade, the Observation Engine examines not only attachments to an e-mail but also the message itself. It searches for active content -- such as code written in Java, JavaScript, or ActiveX -- and embedded URLs that could send recipients to a Web site where malware is automatically downloaded onto visitors’ PCs. Administrators can choose to block, warn or quarantine such messages, officials say.

According to the company, up to 40% of all e-mail messages include URL links or active content of some kind. Of that 40%, 7% send the recipient to a Web site that downloads malicious content.

iSolation Server 4.0 will be available as software that runs at an organization’s gateway or as a service. Pricing will range from $3 to $6 per in-box.

Avinti’s products have traditionally been targeted at small and midsize businesses, but earlier this year the company released an enterprise version of iSolation Server.