I have just returned from...
Now that I am finally able to sit down and write you again...
By now everyone in the world except me seems to have written to congratulate you, but I have been...
I have delayed answering this letter because...
I have been meaning to write ever since I received your letter, but I have had so many important things to do that I just haven't had time.
You will be surprised to get a letter from a perfect stranger.
I hope you don't mind receiving a letter from...
You don't know me so let me introduce myself.
I obtained your name and address from...
I am writing because I understand you would like to have a pen friend in my country.
Your name has been given to me by Mr. X who suggested that I should get in touch with you.
This is just a brief note to thank you for...
I don't know quite how to thank you for...
On behalf of my husband and myself I am writing to thank you for your...
How very kind of you to remember my birthday and what a lovely present!
Now that I am back home I want to write straightaway and thank you for...
Now that I am back at home, I feel that 1 must write and thank you most warmly for all the kindness and hospitality shown to me at your place.
I am afraid this letter is going to hurt you and I hesitated a long time before writing it, but...
I hope you will forgive me for troubling you, but it has occurred to me that you are the only person who may be able to help me.
Please forgive me for troubling you but I would be very grateful if you would help me in a very delicate matter.
I should be grateful if you would...
I want to ask you a very great favor.
I wonder if you would do me a favor.
I don't know how to begin because I have a great favor to ask you.
I am terribly sorry that I could not meet you as planned.
I was sorry to learn that...
There are no words that can express my great/ deep sorrow about...
I was extremely/ terribly sorry to hear of...
We were sincerely/ honestly/ very sorry to hear about your loss.
I feel I must write to tell you how very sorry I am...
I am writing to inquire...
I am interested in the post of... which I saw advertised in...
I am the ideal candidate for the job you have been advertising and I am very anxious to get it.
I would be most grateful if you could send me details of any postgraduate scholarships which you may be offering to students from overseas.
In answer to your inquiry of September 21 about... we are able to inform you that...
We regret to inform you that...
It is with regret that we inform you...
We thank you for your letter and regret that, owing to... we will not be able to help you.