diff --git a/lib/private/Mail/Mailer.php b/lib/private/Mail/Mailer.php
index e438f75d2ce2de083c2c54cce7856c61bcbabf09..d232587df63a26269990503d946c596a8d2f3464 100644
--- a/lib/private/Mail/Mailer.php
+++ b/lib/private/Mail/Mailer.php
@@ -170,7 +170,7 @@ class Mailer implements IMailer {
 		}
 
 		list($name, $domain) = explode('@', $email, 2);
-		$domain = idn_to_ascii($domain);
+		$domain = idn_to_ascii($domain, 0,INTL_IDNA_VARIANT_UTS46);
 		return $name.'@'.$domain;
 	}
 
diff --git a/lib/private/Mail/Message.php b/lib/private/Mail/Message.php
index 5ffc050360aa1dc05846b19ef7150e3abcce7a92..2d3c49d0ce1a5b3e6620040c85f690b4b4e26637 100644
--- a/lib/private/Mail/Message.php
+++ b/lib/private/Mail/Message.php
@@ -58,11 +58,11 @@ class Message {
 		foreach($addresses as $email => $readableName) {
 			if(!is_numeric($email)) {
 				list($name, $domain) = explode('@', $email, 2);
-				$domain = idn_to_ascii($domain);
+				$domain = idn_to_ascii($domain, 0, INTL_IDNA_VARIANT_UTS46);
 				$convertedAddresses[$name.'@'.$domain] = $readableName;
 			} else {
 				list($name, $domain) = explode('@', $readableName, 2);
-				$domain = idn_to_ascii($domain);
+				$domain = idn_to_ascii($domain, 0, INTL_IDNA_VARIANT_UTS46);
 				$convertedAddresses[$email] = $name.'@'.$domain;
 			}
 		}