It depends on the email campaign you´re doing, I would advise to try different contact methods, not just email.Try reaching out in social media profiles, in some cases you may even have a phone number. The only correct answer you will get is by testing out different approaches and see what is working a what isn´t. Also, as @Ahmed Ishak said, check deliverability, the first step is that people actually are getting the emails. I would also advise to give value at first, not try to sell first thing and try to establish a connection before. I hope you get some value out of this comment, have a nice day.🙏