I knew from a source in England that several such letters had been sent and was waiting for one of them to be published. Such letters are not, of course, confidential. They are very carefully written and approved because the Vatican dicasteries know that they will be made public.
Rorate Caeli has the jpeg which is copied above. Fr Z has kindly posted a transcript:
Prot. N. 655/09/L
Rome, 24 July 2009
This Congregation for Divine Worship and Discipline of the Sacraments wishes to acknowldge receipt of your letter dated 22 June 2009 regarding the right of the faithful to receive Holy Communion on the tongue.
This Dicastery observes that its Instruction Redemptionis Sacramentum (25 March 2004) clearly stipulates that "each of the faithful always has the right to receive Holy Communion on the tongue" (n. 92, nor is it licit to deny Holy Communion to any of Christ’s faithful who are not impeded by law from receiving the Holy Eucharist (cf. n. 91).
The Congregation thanks you for bringing this important matter to its attention. Be assured that the appropriate contacts will be made.
May you persevere in faith and love for Our Lord and his Holy Church, and in continued devotion to the Most Blessed Sacrament.
With every good wish and kind regard, I am,
Sincerely Yours in Christ,
(Fr. Anthony Ward, S.M.)