diff --git a/lib/Db/MessageMapper.php b/lib/Db/MessageMapper.php
index 901cd462a6..1e0bde2adf 100644
--- a/lib/Db/MessageMapper.php
+++ b/lib/Db/MessageMapper.php
@@ -36,6 +36,7 @@
 use function array_combine;
 use function array_keys;
 use function array_map;
+use function mb_substr;
 
 class MessageMapper extends QBMapper {
 
@@ -146,7 +147,7 @@ public function insertBulk(Message ...$messages): void {
 
 					$qb2->setParameter('message_id', $messageId, IQueryBuilder::PARAM_INT);
 					$qb2->setParameter('type', $type, IQueryBuilder::PARAM_INT);
-					$qb2->setParameter('label', $recipient->getLabel(), IQueryBuilder::PARAM_STR);
+					$qb2->setParameter('label', mb_substr($recipient->getLabel(), 0, 255), IQueryBuilder::PARAM_STR);
 					$qb2->setParameter('email', $recipient->getEmail(), IQueryBuilder::PARAM_STR);
 
 					$qb2->execute();