Dear Mr. /Ms,
We are very happy to inform you that you have been promoted as (designation) with effect from (due date). In accordance we hereby revise your Gross Salary as Rs /-. Other terms and Conditions remain the same as per the appointment letter.
Kindly sign and return the duplicate of this letter as a token of your acceptance of the above terms and conditions.
With best wishes,
(Name and Your Digital Signature)