Boolean
The switch. On with no recipients is valid and sends nothing. Left out or null keeps it.
Replaces the column selection, which is saved in file order whatever order you send. It can’t be empty. Left out or null keeps it.
[String!]
Replaces every recipient: at most 10 email addresses of at most 254 characters each, trimmed, lowercased and de-duplicated. Left out or null keeps them.