Red-letter day  - A important，special day for some reason

March 4th is always a red-letter day for my wife and me.  3月4日永远是我太太和我的特别的日子。

Today is a fantastic day for us - a real red-letter day! We've just been blessed with our first child - a beautiful baby boy!  今天对我们来说是美妙的一天 - 一个真正值得纪念的日子！承蒙主恩我们的第一个孩子刚刚诞生- 是一个漂亮的男孩！