Port -txsend from str4d #37, https://github.com/zcash/zcash/pull/4522

src/wallet/wallet.cpp

@@ -3950,6 +3950,8 @@ bool CWallet::CommitTransaction(CWalletTx& wtxNew, CReserveKey& reservekey)
         // Track how many getdata requests our transaction gets
         mapRequestCount[wtxNew.GetHash()] = 0;
 
+        std::string strCmd = GetArg("-txsend", "");
+
         if (fBroadcastTransactions)
         {
             // Broadcast
@@ -3962,6 +3964,12 @@ bool CWallet::CommitTransaction(CWalletTx& wtxNew, CReserveKey& reservekey)
             }
             wtxNew.RelayWalletTransaction();
         }
+           // If we are configured to send transactions via an
+        // external service instead of broadcasting, do that
+        else if (!strCmd.empty()) {
+            boost::replace_all(strCmd, "%s", EncodeHexTx(wtxNew));
+            boost::thread t(runCommand, strCmd); // thread runs free
+        }
     }
     return true;
 }