OK, I created a MySql database, made the connection, went to DataAssist and I see the same pages I have always seen (insert, search, update, delete) and there is nothing that even suggest building an email form.
Fact is, Dreamweaver CC 2018 does not work fully with WebAssist. I downloaded the latest Data Bridge and get the exact same errors before. I can use the SendEmail and indeed I can send an email, but the body is empty and there is no way to build the email message.
Maybe you can post a simple copy of the PHP script that should be in the Block.php page and I can customize it. There is a disconnect between the SendEmail script and the message body.
For what its worth, I am attaching the entire error sequence starting from top to bottom even after downloading and reinstalling the latest Data Bridge and attempting to edit Block.php clicking on Server Behaviors.