wildfly-16.0.0.Final: "From address" is no more used as default from in email

As mentioned in the Help (description) of 'Mail Session' configuration:

From: From address that is used as default from, if not set when sending

Apparently this is not the case anymore in wildfly-16.0.0.Final.
For example I made a test with quickstart-16.0/mail/.

When omitting the line
message.setFrom(new InternetAddress(from));

Sending mail fails with:

com.sun.mail.smtp.SMTPSendFailedException: 554-Transaction failed
554 Unauthorized sender address.

I have the same issue when replacing the line above with

message.setFrom(new InternetAddress());

I am pretty sure that this is working in wildfly-15