I work at an organization that frequently hosts webinars. We use marketing cloud to send generic, full subscriber list emails promoting these events. But we also use it to send follow-up emails to those who attended the events.
We often need to create a specialized list of registrants to a program, which I can pull from our website into a .csv file. However, to import it as a list into marketing cloud, it requires 1) an email address and 2) subscriber key. My issue is that I cannot figure out how to search multiple subscriber keys at once. I know how to search one at a time in the "all subscribers" section, but that becomes incredibly tedious when we have lists of 200 to 400 people.
So my problem is these registrants are part of our all subscribers, but sometimes I want to send to a more specific list. However, to send to such a list, I need to find all of their subscriber keys. How can I do this without searching one at a time?