[RadioKid]

It is perfect as a "thank you letter" from Japanese learner. It has some parts which is not natural but it makes Japanese receiver feel your sincerity.

I will write it as follows. It would be too fruent as from foreigner's letter.

思慮深い贈り物 を どうもありがとうございました。日本訪問の記念品に感 謝しています。御社のご繁栄 をお祈りしております。