A good email open rate on Substack typically falls between 40% and 50%. Substack's audience is often highly engaged, as subscribers have opted in specifically to receive content from creators. However, several factors can influence open rates, including the quality of the content, the subject line, the timing of the email, and the relationship between the creator and their audience. To improve open rates on Substack, it's important to build a strong, engaged subscriber base, write compelling subject lines, and send emails consistently. Regularly analyzing performance metrics can help you understand what works best for your specific audience.