#ifdef TCP_FASTOPEN
if (setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
&smtp_connect_backlog, sizeof(smtp_connect_backlog)))
#ifdef TCP_FASTOPEN
if (setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
&smtp_connect_backlog, sizeof(smtp_connect_backlog)))