Try different hyperlinks to see what works best for your audience. You might create three different groups and send each link to your home page, product pages, and blog. You might also try CTA links with different wording, or test an email that includes the same link two or three times. The data will tell you what works. Low click rates may mean your emails aren't compelling, or the information isn't useful for that audience.
The criteria and metrics can be classified according to its type and time span. Regarding the type, we can either evaluate these campaigns "Quantitatively" or "Qualitatively". Quantitative metrics may include "Sales Volume" and "Revenue Increase/Decrease". While qualitative metrics may include the enhanced "Brand awareness, image and health" as well as the "relationship with the customers".

In the 2000s, with more and more Internet users and the birth of iPhone, customers started searching products and making decisions about their needs online first, instead of consulting a salesperson, which created a new problem for the marketing department of a company. In addition, a survey in 2000 in the United Kingdom found that most retailers had not registered their own domain address.[12]These problems made marketers find the digital ways for market development.
Julie Ewald recommends moving away from sending generic content to your whole email list  via e-blast entirely. With a little elbow grease, you can utilize segmentation and start sending off tailored messages to each of your lists with content that’s relevant, valuable, and designed to resonate with the kind of recipients that make up each segment.