How to merge two mailing lists?
To merge the lists, follow the steps below: - Open Contacts tab from the navigation bar and select Manage Lists.
- Click More present in the top right corner.
- Select Merge Lists.
- Select the From list and To list to merge subscribers.
- Click Save.

Note:
Select the Delete "From Lists" after merging check box to delete the existing mailing lists after merging the contacts to a new list.