You can reassure your prospective customers that the emails you send are safe and reliable by following a few simple email marketing etiquette rules:
1. Don't Sensationalise the Headline
The default setting for Yahoo, AOL, Gmail, and the other
popular email providers is to show who the sender is and the headline. In some
instances, the first few words of the email text itself will appear on the
user's email queue.
That makes the headline the first important element of your
email. If it is overly exaggerated, makes extraordinary claims, or is otherwise
sensational, there's a better chance that the email will either be sent
directly to the "Spam" folder or deleted by the user without being read.