Sure, massive sending is also an option, and many are using it. But imagine yourself as a journalist receiving tons of emails every day. Would you click on a cold and formal email? No, right? If you want to have a better opening, share, and reply rate, you have to be personal.
Include the reference of a related-article written by the person you’re contacting. Can’t do better for personalization.
Don’t forget to do follow-up (3 maximum) and add links of your press release if it was published on other important websites.