What does the term 'open rate' refer to in email marketing?

The term 'open rate' in email marketing specifically refers to the metric that measures the number of people who opened an email, expressed as a percentage of the total number of emails delivered. This metric is crucial because it indicates how effective the subject line and sender information are at capturing the attention of the recipients. A higher open rate suggests that the email was appealing enough for recipients to engage with it, which is integral for assessing the overall success of an email campaign.

In the context of the other options, measuring clicks, emails sent, or complaints does not directly correlate with the open rate. While clicks gauge engagement with the content of the email, and total emails sent provides context to the scale of the campaign, neither reflects the direct act of opening the email itself. Complaints, on the other hand, can serve as feedback on the email’s content or relevance but do not pertain to the initial engagement level indicated by open rates.