A software module at an e-mail gateway server scans incoming e-mail messages suspected of being phishing messages and inserts a script program into the head or body of the message in HTML form. The message is converted into an HTML document if necessary. The script program is written in a language such as VBScript, JScript, ECMAScript or JavaScript and can be run in a browser. The modified message is delivered to the recipient. When the e-mail client software on the user's desktop encounters the HTML content a browser starts up and the script program is executed by the browser. The script program can then take any action necessary to counter any hostile content of the message such as providing a warning message, comparing hyperlinks, intercepting a redirect request, warning about suspect attachments, etc.