SMTP/ESMTP

Dangerous Settings
OptionDescription
mynetworks = 0.0.0.0/0With this setting, this SMTP server can send fake emails and thus initialize communication between multiple parties. Another attack possibility would be to spoof the email and read it.
# CAREFUL! Open relay check
sudo nmap -p25,465,587,2525 --script smtp-open-relay <TARGET>

# User enum
# TRY: -M VRFY
smtp-user-enum -v -M RCPT -U <USERLIST> -D <DOMAIN> -t <TARGET>

# Manual enumeration
telnet <TARGET> 25
EHLO <HOSTNAME>
VRFY <USER>  # 250 success; 252 maybe/not; 550 failure
EXPN