Good morning all.
I addressed this question a while ago to eBay, and that message comes up if the seller does not post to your country.
If the seller clicks on Will Post Worldwide, then this message does not appear.
Sometimes there is a contact address at the bottom of the listing with an email address, and in my case I used this to ask the seller if they would post to UK. The answer was, 'generally no', but on this occasion as the item was not delicate, they would.
Hope this answers your question.