Reaching leads from cold emailing is a tough gig. While the average open rate is 5-10%, a salesperson who performs cold outreach the right way reaches the desirable 50-70%.
Always use email checkers in your email marketing plan, I have selected the best tools here https://andrewlaurentiu.medium.com/boost-your-email-sending-with-the-top-5-email-checkers-e6f57b848525