Engagement should be a mandatory element of every online marketing campaign. Its far better to have a customer who is engaged with your (company, website or brand), then one who is not engaged. Engagement Milestones or Markers should be set to evaluate the impact of an online campaign, this way adjustments can be made accordingly if necessary. Engagement allows marketers to evaluate the quality of a lead. For example of you have 2 leads, lead A only opted into your email newsletter while lead B opted in AND "liked" your Facebook page AND gave you a "+1" on Google, it's clear to see which lead is more engaged. Ultimately, greater engagement should yield more conversion and profitability. Just imagine if you had an opted in and highly engaged list, conversions may be easier to generate?