Previously, Internet service providers looked at three particular metrics when assessing the legitimacy of an email sender:

1. How dirty the list is: Are a lot of invalid email addresses being targeted?
2. Spam complaint volume: How often do subscribers hit the “Spam” button?
3. Content: Is the offer spam?

This notion has been turned upside down. AOL Google, Hotmail and Yahoo earn more revenue from engaged consumers; the more ads served up that match consumer preferences, the more revenue each subscriber generates. As a result, it's crucial for such companies to ensure that their email offerings are engaging for their audience, so they are now examining the following:

1. How many people open an email?
2. What percentage of the people who open an email click on the links?
3. How many of the emails are forwarded?

Google is taking this one step further by putting the best performers in the most prominent position as part of its Priority Inbox offering; Google's algorithm makes predictions on which emails are important to the receiver based on email history. Those that are regularly opened and/or responded to will be sent to the Priority Inbox, and according to Google, the determination is made based on “who you've emailed and chatted with most and which keywords appear frequently in the messages you opened recently.”

This is all the more reason to ensure your email marketing campaign is engaging the subscriber. If your email is generating lower open and click-through rates, revamp your campaign so that it resonates with your audience. If not, be prepared for your emails to end up in the “everything else” part of the inbox with the rest of the emails that go unnoticed and unopened.

John Murphy is president of ReachMail (www.reachmail.net), a provider of email marketing services, solutions and advertising.