You have entered a subject or text for the e-mail but no recipients

What causes this issue?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

System Response

The e-mail cannot be sent using the internal system without a recipient
list.

How to fix this error?

Create at least one recipient or choose "Send with Client Program" to
use an e-mail program by adding recipients.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.