587-SMTP

Default conf

cat /etc/postfix/main.cf | grep -v "#" | sed -r "/^\s*$/d"

//telnet - HELO/EHLO
telnet 10.129.14.128 25

//Telnet VRFY
telnet 10.129.14.128 25

//Telnet send an Email
telnet 10.129.14.128 25

Dangerous Setting

mynetworks = 0.0.0.0/0

//Enumeration
sudo nmap 10.129.14.128 -sC -sV -p25

sudo nmap 10.129.14.128 -p25 --script smtp-open-relay -v

nmap IP --script smtp-enum-users.nse

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Swaks

swaks --to [e-mail] --from [e-mail] --server mail.outdated.htb --body "http://10.10.14.54/" --header "Subject:Internal Web App Request"

other side `nc -lvnp 80`     //when someone click the link its show the header.