When writing this question, I found this link: Testing sending mail using Mock Mailer .
Thus, you can access the mail sent by the Mock mailer using the play.libs.Mail.Mock file as follows:
String email = Mail.Mock.getLastMessageReceivedBy(" joe@example.com ");
Mail is returned as a single line, but better than nothing.
At least share it, because it took me a while to find it.
Touko source share