Support

The feature does exist, since 2010 :) The problem is that you're framing your question wrong.

Technically speaking, what you are trying to do is NOT GeoBlocking. GeoBlocking is IP blocking based on the IP-derived country information. You are trying to block requests irrespective of their detected geographic origin. Here's the thing. What you are trying to do is content-based blocking, i.e. whenever unwanted content is present in the submitted request you want the request discarded instead of served. This is exactly what the Anti-spam Bad Words filtering feature does in Admin Tools.

You can add the domains you want to filter as Bad Words, per the documentation page above. Any time someone enters an email address or any other content containing that domain name in the public frontend of your site Admin Tools will block the request and log a security exception with the reason "Bad Words Filtering".

.pl will not work. Bad Words filtering works by doing a pattern search across word boundaries. The dot is a word boundary. You need to enter full domain names there for that trick to work.

Also note that trying to block .pl would be way too generic anyway. It will most certainly filter out content you want and you didn't think would get blocked.

Moreover, this approach for protecting against spam is extremely naive and bound to fail miserably. All Ukrainian, Russian and Arabic-speaking spammers I come across these days use popular, generic mail services (GMail, Yahoo, Hotmail) which you can't afford to block. It's only a matter of time until the regional spammers do the same.

You know what's the obvious solution to your problem? Regular spam filters which classify messages as spam or ham (seriously, the opposite of spam is called "ham") based on content. The drawback is that your contact form email address is no longer whitelisted as safe and you MAY end up losing legitimate email mistakenly marked as spam.

Finally, there's the non-obvious solution to your problem. CAPTCHA. Joomla comes with ReCAPTCHA integration and it can be used in the contact form. It will obviously not work if the spammers employ real, breathing humans to submit the contact form spam instead of bots. You can't fight that.

You're welcome :)