+
+typedef struct smtp_compare_s
+{
+ uschar *current_sender_address;
+ struct transport_instance *tblock;
+} smtp_compare_t;
+
+/*
+Create a unique string that identifies this message, it is based on
+sender_address, helo_data and tls_certificate if enabled. */
+
+static uschar *
+smtp_local_identity(uschar * sender, struct transport_instance * tblock)
+{
+address_item * addr1;
+uschar * if1 = US"";
+uschar * helo1 = US"";
+#ifdef SUPPORT_TLS
+uschar * tlsc1 = US"";
+#endif
+uschar * save_sender_address = sender_address;
+uschar * local_identity = NULL;
+smtp_transport_options_block * ob =
+ (smtp_transport_options_block *)tblock->options_block;
+
+sender_address = sender;
+
+addr1 = deliver_make_addr (sender, TRUE);
+deliver_set_expansions(addr1);
+
+if (ob->interface)
+ if1 = expand_string(ob->interface);
+
+if (ob->helo_data)
+ helo1 = expand_string(ob->helo_data);
+
+#ifdef SUPPORT_TLS
+if (ob->tls_certificate)
+ tlsc1 = expand_string(ob->tls_certificate);
+local_identity = string_sprintf ("%s^%s^%s", if1, helo1, tlsc1);
+#else
+local_identity = string_sprintf ("%s^%s", if1, helo1);
+#endif
+
+deliver_set_expansions(NULL);
+sender_address = save_sender_address;
+
+return local_identity;
+}
+
+
+
+/* This routine is a callback that is called from transport_check_waiting.
+This function will evaluate the incoming message versus the previous
+message. If the incoming message is using a different local identity then
+we will veto this new message. */
+
+static BOOL
+smtp_are_same_identities(uschar * message_id, smtp_compare_t * s_compare)
+{
+uschar * message_local_identity,
+ * current_local_identity,
+ * new_sender_address;
+
+current_local_identity =
+ smtp_local_identity(s_compare->current_sender_address, s_compare->tblock);
+
+if (!(new_sender_address = deliver_get_sender_address(message_id)))
+ return 0;
+
+message_local_identity =
+ smtp_local_identity(new_sender_address, s_compare->tblock);
+
+return Ustrcmp(current_local_identity, message_local_identity) == 0;
+}
+
+
+
+uschar
+ehlo_response(uschar * buf, size_t bsize, uschar checks)
+{
+#ifdef SUPPORT_TLS
+if ( checks & PEER_OFFERED_TLS
+ && pcre_exec(regex_STARTTLS, NULL, CS buf, bsize, 0, PCRE_EOPT, NULL, 0) < 0)
+ checks &= ~PEER_OFFERED_TLS;
+#endif
+
+if ( checks & PEER_OFFERED_IGNQ
+ && pcre_exec(regex_IGNOREQUOTA, NULL, CS buf, bsize, 0,
+ PCRE_EOPT, NULL, 0) < 0)
+ checks &= ~PEER_OFFERED_IGNQ;
+
+if ( checks & PEER_OFFERED_CHUNKING
+ && pcre_exec(regex_CHUNKING, NULL, CS buf, bsize, 0, PCRE_EOPT, NULL, 0) < 0)
+ checks &= ~PEER_OFFERED_CHUNKING;
+
+#ifndef DISABLE_PRDR
+if ( checks & PEER_OFFERED_PRDR
+ && pcre_exec(regex_PRDR, NULL, CS buf, bsize, 0, PCRE_EOPT, NULL, 0) < 0)
+ checks &= ~PEER_OFFERED_PRDR;
+#endif
+
+#ifdef SUPPORT_I18N
+if ( checks & PEER_OFFERED_UTF8
+ && pcre_exec(regex_UTF8, NULL, CS buf, bsize, 0, PCRE_EOPT, NULL, 0) < 0)
+ checks &= ~PEER_OFFERED_UTF8;
+#endif
+
+if ( checks & PEER_OFFERED_DSN
+ && pcre_exec(regex_DSN, NULL, CS buf, bsize, 0, PCRE_EOPT, NULL, 0) < 0)
+ checks &= ~PEER_OFFERED_DSN;
+
+if ( checks & PEER_OFFERED_PIPE
+ && pcre_exec(regex_PIPELINING, NULL, CS buf, bsize, 0,
+ PCRE_EOPT, NULL, 0) < 0)
+ checks &= ~PEER_OFFERED_PIPE;
+
+if ( checks & PEER_OFFERED_SIZE
+ && pcre_exec(regex_SIZE, NULL, CS buf, bsize, 0, PCRE_EOPT, NULL, 0) < 0)
+ checks &= ~PEER_OFFERED_SIZE;
+
+return checks;
+}
+
+