Fedora 9: Change Sendmail SMTP Greeting Message

Each time a connection is made to sendmail, a greeting message is sent. By default, the greeting message contains current the following data:

a. hostname,

b. MTA agent name,

c. sendmail version number

d. and current date.

RFC standards specifies that hostname greeting value should be a fully qualified domain name (FQDN) of the host, but the rest can be customized as you please.

Here's a quick run down of how to change your SMTP greeting message with sendmail.

Change Sendmail SMTP Greeting Message

Basic Requirements

1. Fedora or Linux OS
2. Existing Sendmail Setup

Steps on changing SMTP Sendmail Greeting Message

1. Backup and modify yout /etc/mail/sendmail.mc . By default, this sendmail directive is not included on default sendmail installation. Modify and change WAZZUP to suit your needs.

define(`confSMTP_LOGIN_MSG',`$j WAZZUP')dnl

Save and exit. Recompile your sendmail conf file

# m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

Restart sendmail service

# service sendmail restart

2. Test your newly changed sendmail SMTP greeting message

# telnet your-IP-address 25

should give your new SMTP sendmail greeting. A result from issuing the above command would give a similar result like

Trying 83.83.83.83
Connected to 83.83.83.83.
Escape character is '^]'.
220 ILOVETUX ESMTP
^]
telnet> quit
Take note that, exposing all MTA details, agent versions and other MTA info might also be helpful and enticing to others that could probably lead to certain attacks and vulnerabilities.