+ HDEBUG(D_verify)
+ debug_printf("callout cache: address record is positive\n");
+ }
+ else
+ {
+ HDEBUG(D_verify)
+ debug_printf("callout cache: address record is negative\n");
+ addr->user_message = US"Previous (cached) callout verification failure";
+ *failure_ptr = US"recipient";
+ *yield = FAIL;
+ }
+
+ /* Close the cache database while we actually do the callout for real. */
+
+ dbfn_close(dbm_file);
+ return TRUE;
+ }
+return FALSE;
+}
+
+
+/* Write results to callout cache
+*/
+static void
+cache_callout_write(dbdata_callout_cache * dom_rec, const uschar * domain,
+ int done, dbdata_callout_cache_address * addr_rec, uschar * address_key)
+{
+open_db dbblock;
+open_db *dbm_file = NULL;
+
+/* If we get here with done == TRUE, a successful callout happened, and yield
+will be set OK or FAIL according to the response to the RCPT command.
+Otherwise, we looped through the hosts but couldn't complete the business.
+However, there may be domain-specific information to cache in both cases.
+
+The value of the result field in the new_domain record is ccache_unknown if
+there was an error before or with MAIL FROM:, and errno was not zero,
+implying some kind of I/O error. We don't want to write the cache in that case.
+Otherwise the value is ccache_accept, ccache_reject, or ccache_reject_mfnull. */
+
+if (dom_rec->result != ccache_unknown)
+ if (!(dbm_file = dbfn_open(US"callout", O_RDWR|O_CREAT, &dbblock, FALSE, TRUE)))
+ {
+ HDEBUG(D_verify) debug_printf("callout cache: not available\n");
+ }
+ else
+ {
+ (void)dbfn_write(dbm_file, domain, dom_rec,
+ (int)sizeof(dbdata_callout_cache));
+ HDEBUG(D_verify) debug_printf("wrote callout cache domain record for %s:\n"
+ " result=%d postmaster=%d random=%d\n",
+ domain,
+ dom_rec->result,
+ dom_rec->postmaster_result,
+ dom_rec->random_result);
+ }
+
+/* If a definite result was obtained for the callout, cache it unless caching
+is disabled. */
+
+if (done && addr_rec->result != ccache_unknown)
+ {
+ if (!dbm_file)
+ dbm_file = dbfn_open(US"callout", O_RDWR|O_CREAT, &dbblock, FALSE, TRUE);
+ if (!dbm_file)
+ {
+ HDEBUG(D_verify) debug_printf("no callout cache available\n");
+ }
+ else
+ {
+ (void)dbfn_write(dbm_file, address_key, addr_rec,
+ (int)sizeof(dbdata_callout_cache_address));
+ HDEBUG(D_verify) debug_printf("wrote %s callout cache address record for %s\n",
+ addr_rec->result == ccache_accept ? "positive" : "negative",
+ address_key);
+ }
+ }
+
+if (dbm_file) dbfn_close(dbm_file);
+}
+
+
+/* Cutthrough-multi. If the existing cached cutthrough connection matches
+the one we would make for a subsequent recipient, use it. Send the RCPT TO
+and check the result, nonpipelined as it may be wanted immediately for
+recipient-verification.
+
+It seems simpler to deal with this case separately from the main callout loop.
+We will need to remember it has sent, or not, so that rcpt-acl tail code
+can do it there for the non-rcpt-verify case. For this we keep an addresscount.
+
+Return: TRUE for a definitive result for the recipient
+*/
+static int
+cutthrough_multi(address_item * addr, host_item * host_list,
+ transport_feedback * tf, int * yield)
+{
+BOOL done = FALSE;
+
+if (addr->transport == cutthrough.addr.transport)
+ for (host_item * host = host_list; host; host = host->next)
+ if (Ustrcmp(host->address, cutthrough.host.address) == 0)