I guess your service is also a kind of marketing solutions and would like to provide a feature for Kakaotalk channel, right?
I can’t figure out the service, though, I need to give you more information.
With our APIs you can also send Kakaotalk messages, but it’s not for all users or subscribers.
Instead of it, Kakaotalk channel provides admin website so that administrators can send message on there.
- API : Sending Kakaotalk messages to friends, Configuring user groups on Kakaotalk channel (not sending!)
- Kakaotalk Admin website : Sending Kakaotalk marketing messages to all subscribers or specified user groups
So our messaging API doesn’t meet your requirement.