1. Click the 'Lists & Subscribers' tab on the top navigation bar:
2. Click the list you want to add custom fields to and select 'Custom fields' on the far-right
3. Enter 'deadlinetext' in the 'Field Name' and select 'Text' as the Data Type:
4. Click 'Add custom field' to save the new field:
If you have any questions, please let us know at email@example.com.