And lastly, if an email is really to a single individual, but with a few more individuals copied in (such as a question to an individual developer, but where I want the email trail to be visible to the group), then I would use. Dear Bob (Alice, Charlie, Dilbert) The last one is not a convention I have seen elsewhere, but I find it works for me. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.