Describe a letter. You should say:
When you received it.
Who sent it to you?
What it was about.
Whether it was important to you, and why.

　　1.
　　a) If I had to describe a letter that I received, I would like to tell you about one I received from the visa office.
　　b) I am sure you have received many important letters in your life too.
　　2.
　　a) The letter was to let me know that the authorities had approved my visa application.
　　b) That is to say, I had been informed that my visa would be mailed to me in a few days.