Test it first
You have taken the time to create your Newsletter or email communication, so you want to make sure that it is going out looking its best every time.
You are trying to make a good impression so make sure that you love what you are sending out. Email it to yourself, to a couple of honest friends and make sure that it looks good.
If you have setup things like links to websites or documents then make sure that they work inside the email. I got an email newletter recently that had some advertising in it for a competitor of edmBlast. When I clicked on it and it went to a blank screen. Nice.
Test it... we all make mistakes.