diff --git a/server/mailserver/mail/mail.go b/server/mailserver/mail/mail.go
index 29c69e9f..c3a34ba2 100644
--- a/server/mailserver/mail/mail.go
+++ b/server/mailserver/mail/mail.go
@@ -118,10 +118,20 @@ func (this* mail) isMailUser(accountId string) bool {
 		}
 	}
 	{
+		found := false
 		this.traverseUserGroup(
 			func (groupId int64, group *userGroup) bool {
+				if group != nil {
+					if _, ok := group.userHash.Load(accountId); ok {
+						found = true
+						return false
+					}
+				}
 				return true
 			})
+		if found {
+			return true
+		}
 	}
 	return false
 }