[mjfisher]

Even if people don't have particularly accessible LinkedIn profiles, if you know their names it's often possible to guess or construct an email address for them based on the format of other publicly available emails for the same institution.

There are also tools like https://hunter.io/ and https://rocketreach.co/ which attempt to automate the process for you. I've had very mixed results with those kinds of tools, but they're worth knowing about.