Hi, I've telnetted my unix machines sendmail port, and it came up with this menu. I'm curious what are these options for? And should I be closing this port for security reasons?

Quote: -bash-3.00$ telnet 192.168.0.194 25 Trying 192.168.0.194... Connected to 192.168.0.194. Escape character is '^]'. 220 myunix ESMTP Sendmail 8.13.4+Sun/8.13.3; Mon, 13 Feb 2006 02:59:00 +1100 (EST) HELP 214-2.0.0 This is sendmail version 8.13.4+Sun 214-2.0.0 Topics: 214-2.0.0 HELO EHLO MAIL RCPT DATA 214-2.0.0 RSET NOOP QUIT HELP VRFY 214-2.0.0 EXPN VERB ETRN DSN 214-2.0.0 For more info use "HELP <topic>". 214-2.0.0 To report bugs in the implementation contact Sun Microsystems 214-2.0.0 Technical Support. 214-2.0.0 For local information send email to Postmaster at your site. 214 2.0.0 End of HELP info

Thanks.

You can use the commands to send mail :P
Here is an example of sending mail with SMTP and retrieving mail from a POP3 server using the protocol commands.
The link also has references to the RFC's for SMTP and POP3.

I have never heared of any security hazard with smtp, but it never hurts to close it if you dont use it.

Yes, you'll want to close this port unless you are actually running a mail server (not just using a mail account, but running your own mail account on that machine).