-BOOL good_response = smtp_read_response(sx, sx->buffer, sizeof(sx->buffer),
+BOOL good_response;
+#if defined(__linux__) && defined(TCP_QUICKACK)
+ { /* Hack to get QUICKACK disabled; has to be right after 3whs, and has to on->off */
+ int sock = sx->cctx.sock;
+ struct pollfd p = {.fd = sock, .events = POLLOUT};
+ int rc = poll(&p, 1, 1000);
+ (void) setsockopt(sock, IPPROTO_TCP, TCP_QUICKACK, US &on, sizeof(on));
+ (void) setsockopt(sock, IPPROTO_TCP, TCP_QUICKACK, US &off, sizeof(off));
+ }
+#endif
+good_response = smtp_read_response(sx, sx->buffer, sizeof(sx->buffer),