Should I use commas after sign-ons and sign-offs?
You can choose to put commas after these or not; it's entirely up to you.
However, you need to be consistent in this area, so if you choose to put a comma after your sign-on, be sure to also put one after your sign-off. Similarly, if you choose to NOT put a comma after your sign-on, do not put one after your sign-off.
