I call into oil & gas companies as well as hospitals, and when I magically get a hold of a prospect that's interested in learning more, I often find that they didn't get any of my e-mails due to their org's firewall. My first e-mails never have any links in them, even in the signature.
Would you reach out on LinkedIn to ask if they received your e-mail? Are there ways to get around firewall? Any creative ideas out there?