Phone, email or letter?
Email, with a request for a phone call.
Without truly understanding the context, it feels like the best option you have is the phone. Will allow you to be more personal and address any concerns in the moment. That being said, logic would say this should be an in-person if at all possible.
I recently licensed a patent to a business. There was a great deal of market research and market understanding that we used to develop a list of prospects. Once you have prospects, you can target key contacts within businesses and organizations that could benefit from the intellectual property. The key is not just have a concept, but materials that effectively communicate the value proposition for the business, without selling. Infographics will become value when clearly demonstrating the market opportunity for the business -- without them having to think too deeply. When it's a fit for their gap and you've jumped ahead and solved a problem they hadn't spent the time or money developing yet, the licensing opportunity emerges.
For us, the license worked best when the business had a vast distribution network, organized logistics, and processes to implement the IP. We stayed on to support the technical implementation and gained extra service fees from expertise in the concept/IP, product integration, and implementation. That was a second revenue stream in our sell that you may also pursue.
No guess without a great deal of context.
Tip: The way I handle this for myself + clients, when digital assets are involved is to use an API service + sell access to the API service for fixed period of time with sale completion at end of period.
This approach can also be used for any IP (intellectual property) or physical goods/services/information.
Likely best to pick a few Clarify posters you feel comfortable with + talk through your specifics on phone calls.
What you're asking can have many complex variations.
Trying to... glean an answer from Clarity comments... will likely cause you to miss many opportunities for optimization your sale/income proceeds.