A bird that isn't native to Fire Country would fly into the Konoha Aviary Express. A hawk that would ruffle its feathers and perch itself waiting for the recipient of the letter to come its way.
The hawk would take its leave back to Lightning Country once the letter was taken off of its leg.
Dear lord Hokage,
Firstly, I would like to congratulate you on your ascension to becoming the Sixth Hokage. We have updated our own bingo books with the one that you have given us and we also thank you for doing your own parts in watching Sunagakure for any events that might spill out of the Wind Country. Please be assured that we will remain committed to our treaties with your great nation and share your desire for stability and prosperity for the Village hidden in the Leaves. And personally, I look forward to seeing how you propel the future of Leaf as the memories of your Village has given me fond moments to think back on.
Shinrya Kitsune
Eleventh Raikage
Firstly, I would like to congratulate you on your ascension to becoming the Sixth Hokage. We have updated our own bingo books with the one that you have given us and we also thank you for doing your own parts in watching Sunagakure for any events that might spill out of the Wind Country. Please be assured that we will remain committed to our treaties with your great nation and share your desire for stability and prosperity for the Village hidden in the Leaves. And personally, I look forward to seeing how you propel the future of Leaf as the memories of your Village has given me fond moments to think back on.
Shinrya Kitsune
Eleventh Raikage
The hawk would take its leave back to Lightning Country once the letter was taken off of its leg.