Add missing import

diff --git a/wcfsetup/install/files/lib/system/email/Email.class.php b/wcfsetup/install/files/lib/system/email/Email.class.php
index aff8a132d290870fd4a28b8471a78ec59c3bca81..361c9ab905e20f1ba23a1389bfd570f0c5e3d200 100644 (file)
--- a/wcfsetup/install/files/lib/system/email/Email.class.php
+++ b/wcfsetup/install/files/lib/system/email/Email.class.php
@@ -8,6 +8,7 @@ use wcf\system\email\mime\AbstractMimePart;
 use wcf\system\email\mime\IRecipientAwareMimePart;
 use wcf\system\event\EventHandler;
 use wcf\util\DateUtil;
+use wcf\util\HeaderUtil;
 use wcf\util\StringUtil;
 
 /**