If one uses comma separated list of email addresses in To, Cc and such fields, the task produces an error:
At least one recipient is not valid., Recipient ' email.address@frends.com' is not resolved. All recipients must be resolved before a message can be submitted.
The old SendEmail task accepted comma as separator and currently there are multiple integrations out there that use the comma syntax. Developers would easily continue to use it.
Note the space in the address.
If user uses comma, perhaps it should be replaced in the task with a semicolon and the addresses could be trimmed.