[TASK] Prefill test email field with be user email

Classes/Controller/MailController.php

@@ -205,6 +205,7 @@ class MailController extends ActionController {
 
 		$this->view->assign('docHeader', $this->docHeaderComponent->docHeaderContent());
 		$this->view->assign('typo3Version', VersionNumberUtility::convertVersionNumberToInteger(TYPO3_version));
+		$this->view->assign('beUserMail',  $GLOBALS['BE_USER']->user['email']);
 	}
 
 	/**

Resources/Private/Templates/Mail/Index.html

@@ -70,7 +70,7 @@
 			</div>
 			<f:form class="col-md-12" method="post" controller="Mail" action="sendTestMail">
 				<f:form.submit class="btn-primary btn form-group" value="{f:translate(key:'backend.send_test')}" />
-				<f:form.textfield name="emailAddress" type="email" required="TRUE" class="email-input form-group" placeholder="{f:translate(key:'backend.email')}" />
+				<f:form.textfield name="emailAddress" type="email" required="TRUE" class="email-input form-group" value="{beUserMail}" />
 				<f:form.hidden name="selectedLanguageLeft" value="{selectedLanguageLeft}" />
 				<f:form.hidden name="selectedLanguageRight" value="{selectedLanguageRight}" />
 				<f:form.hidden name="selectedTemplate" value="{selectedTemplateKey}" />