Is the name of the text message sent to the leader followed by a comma or colon?

Do you care so much? It doesn't really matter. If you want a standard format, you'd better use a colon. The specific format is as follows:

XXX leader:

Hello.

(text) .................................................................

…………………………………………………………………………………………………………………

hope

Good health (as long as it is this kind of congratulations, it doesn't have to be "good health")

XXX (your name)

(time)

This is the format of the letter, but texting is ok. I hope I can help you.