You have done such a great job handling the (job title) responsibilities. I really like the way you've taken charge of this area and implemented new changes. I think your ideas are very useful and will make a positive contribution to (company).
Because we have been...
Dear (recipient's name),
You have done such a great job handling the (job title) responsibilities. I really like the way you've taken charge of this area and implemented new changes. I think your ideas are very useful and will make a positive contribution to (company).
Because we have been so satisfied with your work, we would like you to resume this responsibility full time. You will be released from your previous responsibilities and will assume the (job title) responsibilities effective (date). I'm excited for you to continue to develop this area of the company.
Sincerely,
(your name)
