Hello, I'm hoping it would be possible for the Opt-in Form to support an additional email subcription/list provider "MailEnable".
We use MailEnable as an on premise email solution, which supports subscription on all versions of their product.
https://www.mailenable.com/features/list-server.asp
This would be a much prefered option over subscribing to an online service, as we would like to keep this information in house.