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Hi Tim,

That's not really a valid/reliable way to check an e-mail address. While you can _probably_ get it to work, any e-mail that happens to contain a telnet IAC character will cause things to go haywire.

Furthermore, you are telling the e-mail server that you are going to send a message, and then assuming that it will reject the message if the destination address if incorrect. That's not reliable.

1) You need to make sure you're connecting to a valid mail-exchanger for the destination address. That's not the same as a simple DNS lookup on 'yourdomain.com', you need to look up the MX records, and only fall back to the address (A record) if the MX records aren't found. Telnet clients won't do that.

2) Many sites will accept messages for invalid e-mail addresses, and then either silently discard them, or forward them to an administrator, or attempt to relay the message. You can't simply assume that an e-mail address is valid just because it's accepted.

3) The IAC character thing I mentioned.

Want a better way? I'd suggest using (or writing) e-mail software instead of telnet software. That'll give you the ability to solve problems 1 & 3, above.

There's no solution for #2. There simply isn't a way to completely validate an e-mail address, aside from sending mail to it and getting a response back. This has been discussed dozens and hundreds and millions and zillions of times on Midrange.com. People hide their e-mail addresses to avoid spam.


On 11/9/2010 12:43 PM, tim.dclinc@xxxxxxxxx wrote:
I found a technique to validate an email address using telnet port 25 as
follows:

telnet smtpserver:25

then type the following

helo<yourdomain.com>
mail from:<info@xxxxxxxxxxxxxx>
rcpt to:<jimbsa2aa4@smtpserver>


If there is a better way of doing this, im up for it.

Here are two sites for reference
http://verify-email-address.org
http://www.barattalo.it/demo/dosmtpvalidation.php#


-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Scott Klement
Sent: Tuesday, November 09, 2010 12:59 PM
To: Midrange Systems Technical Discussion
Subject: Re: can the telnet command be automated?

I thought you were trying to automate a telnet connection? If so, why
are you connecting to an SMTP (e-mail) port?!


On 11/9/2010 10:22 AM, tim.dclinc@xxxxxxxxx wrote:
Im trying to work with PASE TELNET using the technique discussed, but it
locks up and doesn't complete the script.

Here is the qsh command I am using
QSH CMD('(/curl -v telnet://74.125.45.27:25</tmp/pase/stdin.txt )')

Here is the script file.
HELO<barattalo.it>
MAIL FROM:<info@xxxxxxxxxxxx>
RCPT TO:<sample@xxxxxxxxxx>

Here is the output:
* About to connect() to 74.125.45.27 port 25
* Trying 74.125.45.27... connected
* Connected to 74.125.45.27 (74.125.45.27) port 25
220 mx.google.com ESMTP b20si14035801ana.185
250 mx.google.com at your service

It just sits on this display. I cant get out of the session without using
System Request opt 2

Any suggestions?





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