You can try to do it at database level, there is no other way.
Or export that list, remove half contacts, reimport the kept half associating a new list.
While not reducing the sending speed instead of splitting a list?
When importing half to the new list, shall I be doing Update or Overwrite? Because they will already be in list 1. I want to put half of them in the new list 2 only and not in the old list 1.
I think you need to add a bit of explanation as to what “existing preferences” are.
Hi Stefano, can you let me know if I shall be using Update or Overwrite to import the other half into the new list? Thank you.