Ideally, your email newsletter is going to look like it’s part of your brand. In other words, you’ll include your logo, and may also include the same photo or avatar you use across social media. That’ll help recipients recognize you, which boosts trust, and therefore engagement.
For subscribers, consistency is key, so don’t switch email newsletter design templates randomly. Instead, use the same template for the same type of email so they know what to expect, can become familiar with it, and even look forward to it.