What do you mean, life is suddenly like sending a letter, and it's sunny?

This sentence means that a person's life is like living in a temporary place, and time is fleeting.

This sentence comes from Yang Wanli, an ancient China writer, "My Feeling of Going Out of the Hedge Door to Meet the Cold in Autumn Night". "Life is like mail, you don't have to worry about fine weather" means that a person's life is like living in a temporary place, and time is fleeting. So cherish the time and don't live up to the beautiful weather and opportunities. This sentence reminds people to cherish every day, seize every moment, don't waste time, but actively pursue their goals and dreams.