I have often written part of my message to the addressee in the address space on a postcard, and as far as I know most of the cards that I've sent over the years have arrived without any problem whenever I've done this no matter which country I sent them from and to. I have also often received postcards with the message spilling over into the address space.
After all, if there's empty space why not use it as long as the address is still clear and legible?
But I wonder if it is officially allowed. Opinion seems to vary on this, and I believe that the rules about where you may write on a postcard vary from country to country. For example I seem to recall that until fairly recently postcards sold in Italy had a line near the bottom marked "Do not write below this line". Not sure if that's still the case.
I presume you will only usually get away with writing in the address space on postcards sent within the UK or if it's allowed in both the country of origin and the destination country, as every international item of mail is presumably processed by the mail systems of both countries.
After all, if there's empty space why not use it as long as the address is still clear and legible?
But I wonder if it is officially allowed. Opinion seems to vary on this, and I believe that the rules about where you may write on a postcard vary from country to country. For example I seem to recall that until fairly recently postcards sold in Italy had a line near the bottom marked "Do not write below this line". Not sure if that's still the case.
I presume you will only usually get away with writing in the address space on postcards sent within the UK or if it's allowed in both the country of origin and the destination country, as every international item of mail is presumably processed by the mail systems of both countries.