diff --git a/src/Object/EMail/IEmail.php b/src/Object/EMail/IEmail.php
index f1e66a224f..9fd1fe3da6 100644
--- a/src/Object/EMail/IEmail.php
+++ b/src/Object/EMail/IEmail.php
@@ -80,7 +80,7 @@ interface IEmail extends JsonSerializable
 	 *
 	 * @return string
 	 */
-	function getMessage(bool $plain = false);
+	function getMessage(bool $plain = false): string;
 
 	/**
 	 * Gets the additional mail header array
diff --git a/src/Object/Email.php b/src/Object/Email.php
index 57eb0c17e9..4d5a11715c 100644
--- a/src/Object/Email.php
+++ b/src/Object/Email.php
@@ -110,12 +110,12 @@ class Email implements IEmail
 	/**
 	 * {@inheritDoc}
 	 */
-	public function getMessage(bool $plain = false)
+	public function getMessage(bool $plain = false): string
 	{
 		if ($plain) {
 			return $this->msgText;
 		} else {
-			return $this->msgHtml;
+			return $this->msgHtml ?? '';
 		}
 	}