“we just do a simple broadcast that goes out to the list and says hey we want to make like we're working on the next kind of like our future content calendar and we want to make sure that what we're creating aligns with you and your needs what do you remind or would you mind replying to this email with one or two sentences”

Validate audience with one broadcast reply email

If you have no idea who's actually on your list, send one plain-text broadcast asking for a one-or-two-sentence reply about who they are and what they want. Normalize the top three or four themes into a V1 segmentation, ignore the outliers, and ship. This is the cheapest audience research in existence and takes one hour.