frontend ft_smtp
bind 0.0.0.0:25 transparent
mode tcp
no option http-server-close
timeout client 1m
log global
option tcplog
default_backend bk_relay

backend bk_relay
mode tcp
no option http-server-close
log global
option tcplog
timeout server 1m
timeout connect 5s
balance roundrobin
server s1 10.10.1.2:25
server s2 10.10.10.1.5:25