Your website is blocked by Netcraft, not Opera itself. We use their blacklist to protect Opera users from fraud attempts. This will also affect your site in any other browser where the user has installed the popular Netcraft toolbar.
In order to unblock your website, please contact Netcraft. If they have incorrectly labelled your site as containing fraudulent content, you can contact them using the details here: https://toolbar.netcraft.com/report_mistake. You can see their report about your site here: https://toolbar.netcraft.com/site_report.
Note that there are a number of ways a legitimate site could contain fraudulent content:
- The server may have been hacked and malware or fraudulent content was installed on it. This is sometimes hidden in a folder that does not appear on FTP or with common command line tools (e.g. there is a common rootkit that hides things in a folder called /.sk/ and then modifies the command line tools so that they never show it).
- If the site includes scripts, images, iframes, or stylesheets from other websites, any of those could have been compromised and could, therefore, deliver fraudulent content when used as part of the site.
Netcraft will check for these cases when they scan the site, or before removing it from their listings. Netcraft also use a heuristic to detect newly discovered sites that are at high risk of being used for fraud, even if those sites are in fact clean. This could be what made them list your site highly in their risk rating.
Please follow up with Netcraft if your site continues to be blocked by their fraud listings.