@ParameterizedTest
    @ValueSource(booleans = {true, false})
    void verifyOperation(final boolean html) throws Exception {
        val principal = RegisteredServiceTestUtils.getPrincipal("casuser",
            Map.of("email", List.of("mm1844@gmail.com")));
        val emailRequest = EmailMessageRequest.builder()
            .locale(Locale.GERMANY)
            .body("This is the email body")
            .emailProperties(new EmailProperties()
                .setHtml(html)
                .setCc(List.of("mm1844@gmail.com"))
                .setBcc(List.of("mm1844@gmail.com"))
                .setSubject("This is the subject")
                .setFrom("mm1844@gmail.com"))
            .attribute("email")
            .principal(principal)
            .build();
        assertFalse(emailSender.send(emailRequest).isSuccess());
    }
This is {@link MailgunEmailSenderTests}.

@author Misagh Moayyed
@since 7.2.0
support/cas-server-support-mailgun/src/test/java/org/apereo/cas/mail/MailgunEmailSenderTests.java