diff --git a/server/mailserver/mail/mail.go b/server/mailserver/mail/mail.go
index b82ffe21..e851b2f3 100644
--- a/server/mailserver/mail/mail.go
+++ b/server/mailserver/mail/mail.go
@@ -22,6 +22,7 @@ type mail struct {
 	userRegStartTime int32
 	userRegEndTime int32
 	attachments []*attachment
+	recipients map[string]int32
 	userGroups *sync.Map
 }