diff --git a/notifier/mailto.c b/notifier/mailto.c
index 65955090e9..0ff63f1ada 100644
--- a/notifier/mailto.c
+++ b/notifier/mailto.c
@@ -263,7 +263,7 @@ copy_validate_address(
       goto bad_address;
     }
     else if (!strchr("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
-                     "0123456789!#$%&\'*+-/=?^_`{|}~", *bufptr))
+                     "0123456789!#$%&\'*+-/=?^_`{|}~.", *bufptr))
     {
      /*
       * Not an allowed address character...