# while true; do date | tr '\n' ' ' && /usr/local/nagios/libexec/check_smtp -H somemailhost -p 25 ; sleep 5s; done;
Fri Aug 7 11:15:35 MST 2015 SMTP OK - 0.108 sec. response time|time=0.108085s;;;0.000000
Fri Aug 7 11:15:41 MST 2015 SMTP OK - 0.111 sec. response time|time=0.111096s;;;0.000000
Fri Aug 7 11:15:46 MST 2015 SMTP OK - 0.110 sec. response time|time=0.110013s;;;0.000000