You can start by searching on various websites belonging to companies or organizations within the desired industry. Many websites offering advertising also have newsletters as part of their ad strategy. You can often find their ad channels via their media kit. If the information isn't directly available on the website, you can always reach out to the website. However, the quickest and most effective way to find a list for newsletter dispatches is to use platforms like Ocast.com, where you can find a compilation of different operators offering newsletters as an advertising channel. On Ocast, you can easily compare different newsletters based on their reach, audience, and cost. Request a quote via Ocast to get a better understanding of the costs and compare different options against each other.