What key metric can be measured to evaluate email campaign success?

The key metric to evaluate email campaign success is the engagement score. This metric provides insight into how recipients are interacting with the email, factoring in elements such as open rates, click-through rates, and overall engagement levels. High engagement scores indicate that the email content resonates with the audience, prompting them to take the desired action.

Other options, while potentially informative in certain contexts, do not directly reflect the performance of an email campaign. For example, assessing color scheme effectiveness is a more subjective measure that pertains to design rather than the actionable results of the campaign. Similarly, the form field completion ratio is relevant for forms, not specifically for email campaigns, as it indicates how effectively forms capture leads rather than how well an email performs. Lastly, the number of emails sent does not inherently indicate success; a high volume of emails could lead to lower engagement levels if not targeted appropriately. Therefore, the engagement score is the most relevant and reliable metric for gauging email campaign effectiveness.