1)
Dear
It was with great pleasure that I read of your promotion
to the position of (position) with (name of firm)
I am sure your firm has made a very wise choice and that
you will excel in your new role as (position)
Please accept my congratulation on your promotion and my
very best wishes for your continuing success.
2)
Dear
Congratulations on your recent promotion to (position)
I know how hard you have worked to earn the recognition
you presently enjoy at (name of firm) ,and I feel that
they are very wise in having made their choice.
Please accept our best wishes for your success in your
new position.