instant in the sense that sending it doesn't take 3-5 business days. they're not necessarily meant to be tweets, although there's nothing wrong with using email

instant in the sense that sending it doesn't take 3-5 business days. they're not necessarily meant to be tweets, although there's nothing wrong with using email for a system like that. they're not slowing anything down, in my opinion. they're to be used when necessary, just like most things. besides, after the initial email in a chain it seems that the trend is to drop that greeting anyways. there are issues larger than writing "Greetings" in your email that you can solve. :P