+/* Construct the list of domains from the ARC chain after validation */
+
+uschar *
+fn_arc_domains(void)
+{
+arc_set * as;
+unsigned inst;
+gstring * g = NULL;
+
+for (as = arc_verify_ctx.arcset_chain, inst = 1; as; as = as->next, inst++)
+ {
+ arc_line * hdr_as = as->hdr_as;
+ if (hdr_as)
+ {
+ blob * d = &hdr_as->d;
+
+ for (; inst < as->instance; inst++)
+ g = string_catn(g, US":", 1);
+
+ g = d->data && d->len
+ ? string_append_listele_n(g, ':', d->data, d->len)
+ : string_catn(g, US":", 1);
+ }
+ else
+ g = string_catn(g, US":", 1);
+ }
+return g ? g->s : US"";
+}
+
+
+/* Construct an Authentication-Results header portion, for the ARC module */