SMTP

Documentation

• http://www.networksorcery.com/enp/rfc/rfc2821.txt
• How to check an SMTP connection with a manual telnet session

 

SMTP reply codes

• http://www.greenend.org.uk/rjk/2000/05/21/smtp-replies.html
• http://www.networksorcery.com/enp/protocol/smtp.htm
• RFC 3464
• [1]

• 5.5.0 unavailable (bob knows why)
• 5.1.1 something wrong on exchange sewer, probably user unknown
• 5.2.2 over quota

test smtp auth

echo -n "\0username\0password"| base64
openssl s_client -connect smtp.example.com:587 -starttls
HELO somehostname
AUTH PLAIN MzIwOTQyODUyMjYyNg==