Inactive Tutor answered 03/22/19
You insert commas before and parenthetical expressions, which are words inserted into a sentence giving information that isn't essential. The commas are used correctly in the examples you provided, but there are other ways to write it. For example, if this a letter or email then it would be redundant to write the recipient's name within the body of the letter, so you can safely drop it from the sentence. Another option would be to break them into two smaller sentences: "Thank you for writing me back, Michelle. All the best to you in 2019!"