If we start a correspondence with 'Hi' or 'Hello,' does a comma or period follow? Hi, I am writing to say ... And, if 'Thanks'/'Thank you' is used to close out a correspondence (and nothing else), would a period or comma follow each? Hi Joe, I am writing to say... Thank you, <---comma or period here? John
Comma or colon in the first instance (colon's usually used with just a name, not a salutation, I think), comma or period in the second. Commas are still considered more casual, but I've used them in more business-y correspondences and it's been fine. It's really not too big of a deal, I don't think People will understand what you're saying.
Both of your examples are correct. There is a comma after the salutation and a comma after the "thank you," then your name goes on the next line down. izzybot is also correct in saying that if you just use a name, you could use a colon "Joe:" but you wouldn't do that with a salutation. A comma also works if you just have a name: "Joe,"
I've always thought that Hi Joe incorrectly derived from Dear Joe. If we were writing dialogue, we would write Hi, Joe. Hi, Joe: Howyadoin, Joe? Thank you, John