Dear Sir,
Mr._________ has applied for the post of Assistant in our office and has submitted a service certificate of four years from your office.We shall feel highly obliged if you can give us your candid opinion whether we should offer him a job he applied for.
Any information furnished to us by you, shall be treated strictly confidential.If an opportunity arises, we shall be glad to reciprocate
Thanking you,
Yours faithfully,