Are you continuing to pursue leads despite knowing they typically don’t engage with external recruiters or agencies?

About a month ago, my company closed its doors, which prompted me to embark on a more independent journey in recruitment. As I reach out to potential clients, I’m realizing that I’m still learning the ropes of sales. I’m curious about how to handle this situation: if a company mentions a policy against working with external recruiters and agencies, is it worth persistently following up? What strategies can I use in this scenario?