extern type serial;
{{Domain zone serial numbers}}
extern val serialAuto : serial;
-{{Whenever DNS data changes, choose a sensible serial number automatically.}
+{{Whenever DNS data changes, choose a sensible serial number automatically.}}
extern val serialConst : int -> serial;
{{Use this particular serial number.}}
extern val domain : your_domain -> Domain => [Root] {DNS : dnsKind, TTL : int};
{{Configure a domain to which you have access rights.}}
+
+extern type mail_node;
+{{A node offering SMTP services}}
+extern val mail_node_to_node : mail_node -> node;
\ No newline at end of file