Thanks for your last letter.
I am writing just to inform you ……
In reply to your last letter, I am writing to explain the twoquestions as follows: …
I have the pleasure to tell you that„
I’m very much delighted to inform you that„
I apologize for not writing to you for a long time„
I must apologize for my delay in answering your letter„
I’m very happy to hear that you are all enjoying goodhealth.
It is good to hear from you and I shall be very pleased tolet you have the information you need.
I’m very pleased to hear that everything is going sowell with you.