diff --git a/mail/locales/en-US/chrome/messenger/templateUtils.properties b/mail/locales/en-US/chrome/messenger/templateUtils.properties
new file mode 100644
index 0000000000..f35dc3436a
--- /dev/null
+++ b/mail/locales/en-US/chrome/messenger/templateUtils.properties
@@ -0,0 +1,5 @@
+# LOCALIZATION NOTE yesterday: used in various places where we compute
+# a "friendly" date, e.g. displaying that a message was from yesterday.
+
+yesterday=yesterday
+