diff --git a/odoo/tools/mail.py b/odoo/tools/mail.py
index 609af0289f3..56da8dd4194 100644
--- a/odoo/tools/mail.py
+++ b/odoo/tools/mail.py
@@ -39,7 +39,7 @@ safe_attrs = clean.defs.safe_attrs | frozenset(
      'data-o-mail-quote',  # quote detection
      'data-oe-model', 'data-oe-id', 'data-oe-field', 'data-oe-type', 'data-oe-expression', 'data-oe-translation-id', 'data-oe-nodeid',
      'data-publish', 'data-id', 'data-res_id', 'data-interval', 'data-member_id', 'data-scroll-background-ratio', 'data-view-id',
-     'data-class',
+     'data-class', 'data-mimetype',
      ])