SMTP Open Relay

A short walkthrough of how to use manual SMTP open relay manually and also through an nmap script.

SMTP Open Relay Commands

ncat -C <ip address>
HELO mail.co.uk
MAIL FROM: <[e-mail]>
RCPT TO: <[e-mail]>
DATA
Test Email

Nmap Script

nmap --script smtp-open-relay.nse [--script-args smtp-open-relay.domain=<domain>,smtp-open-relay.ip=<address>,...] -p 25,465,587 <host>
Host script results:
| smtp-open-relay: Server is an open relay (1/16 tests)
|_MAIL FROM:<[e-mail]> -> RCPT TO:<[e-mail]>