SMTP... telnet to port 25

[Jessica Chou]

Can I specify "Reply-To" besides "Mail from" and "Rcpt To", when I directly telnet to a mail server's port 25 (smtp)?

Thank you.

Jessica

[Douglas Cromby_1]

Hello Jessica,

It does not appear that there is a Reply to option, at least using sendmail 8.9.3. This is what I saw when I did help when telnetted into port 25 on one of my servers:

help
214-This is Sendmail version 8.9.3 (PHNE_18979)
214-Topics:
214- HELO EHLO MAIL RCPT DATA
214- RSET NOOP QUIT HELP VRFY
214- EXPN VERB ETRN DSN
214-For more info use "HELP ".
214-To report bugs in the implementation or suggestions for
214-future enhancements, contact your HP representative.
214-For local information send email to Postmaster at your site.
214 End of HELP info

I hope that this helps.

[Dave Kelly_1 · Accepted solution]

Reply-To is part of the ARPA header and should be specified in the DATA section of the message as in this example:

220 host.domain.com ESMTP Sendmail 8.8.6 (PHNE_14041)/8.8.6; Fri, 27 Oct 20
00 08:56:37 +0100 (BST)
helo domain.com
250 host.domain.com Hello root@localhost, pleased to meet you
mail from: user1@domain.com
250 user1@domain.com... Sender ok
rcpt to: user2@another.domain.com
250 user2@another.domain.com... Recipient ok
data
354 Enter mail, end with "." on a line by itself
Reply-To: user3@domain.com
Subject: Test Message

Hello
.
250 IAA13263 Message accepted for delivery

[CHRIS_ANORUO]

Telnet server 25 (If you get a response and your sendmail.cf file is set), once connected, type:
Hello HP, (you will get ok prompt reply)
MAIL FROM:(your server name e.g. unixbox)

RCPT TO: (who you want to send it to i.e. hp@agilent.com)
DATA
Send data. End with CRLF.CRLF
(enter your message)
test message
.
The recipient should receive the email.

[Josh_13]

beware. most places now log users giving you a random id number and logging your ip along with it, so if you think you can use this to send things to screw with ppl, think again.