Set your buyer requirements to exclude buyers in countries to which you don’t post.

Set your postage options to exclude countries to which you don’t post.

That will sort out that issue.

But… if you haven’t sold recently and regularly, are you aware of the hold on funds until eBay seems you are no longer new?

Make sure you are fully verified for Managed Payments (including having uploaded photo ID and also having verified your bank account as eBay now require). If this isn’t done, you’ll never get your payment.

Don’t list on eBay unless you have read the eBay Help pages on Selling. It’s all very different since Managed Payments came in.

Requiring immediate payment will also weed out some scammers.