diff --git a/pith/reply.c b/pith/reply.c
index ab4e97c..d7bdc91 100644
--- a/pith/reply.c
+++ b/pith/reply.c
@@ -3369,13 +3369,17 @@ generate_message_id(void)
 
     get_alpine_revision_number(revisionbuf, sizeof(revisionbuf));
     if(F_ON(F_ROT13_MESSAGE_ID, ps_global)){
-       hostpart       = rot13(ps_global->hostname);
+       hostpart       = rot13(ps_global->userdomain
+			       ? ps_global->userdomain
+			       : ps_global->hostname);
        alpine_name    = rot13("alpine");
        alpine_version = rot5n(ALPINE_VERSION);
        system_os      = rot13(SYSTYPE);
        revision	      = rot5n(revisionbuf);
     } else {
-       hostpart	      = cpystr(ps_global->hostname);
+       hostpart       = cpystr(ps_global->userdomain
+			        ? ps_global->userdomain
+			        : ps_global->hostname);
        alpine_name    = cpystr("alpine");
        alpine_version = cpystr(ALPINE_VERSION);
        system_os      = cpystr(SYSTYPE);