On Sat, 3 Nov 2007 13:22:18 -0500
forgottenwizard <[EMAIL PROTECTED]> wrote:
> I'm not sure what the purpose of telneting my own system it, either.
> Would I be looking for an open port?
Telnet clients are useful debugging tools. You can connect to a
service (in this case SMTP, on port 25) and then manually implement the
service's protocol for troubleshooting purposes.
For Example, in this case my message couldn't be sent because it
(evidently) contained an invalid header, but the same commands would
work if connected to a different server. I can see the error message;
if I was maintaining this server, I could perhaps adjust my
proxyd-filter.pl file, or suggest that my users adjust their mail
headers.
====================================================================
Example SMTP session, implemented through telnet.
------------------------------------------------------
[EMAIL PROTECTED] ~ $ telnet mx4.hushmail.com 25
Trying 65.39.178.137...
Connected to mx4.hushmail.com.
Escape character is '^]'.
220 smtp6.hushmail.com ESMTP Postfix
HELO spore.ath.cx
250 smtp6.hushmail.com
MAIL FROM: [EMAIL PROTECTED]
250 2.1.0 Ok
RCPT TO: [EMAIL PROTECTED]
250 2.1.5 Ok
DATAHello forgottenwizard,
502 5.5.2 Error: command not recognized
DATA
354 End data with <CR><LF>.<CR><LF>
Hello forgottenwizard,
This email is meant as an example of the usefulness of a telnet client
as a general purpose debugging tool, applicable to all sorts of
plain-text communication protocols. In this case, I spoke SMTP with
the mail server. You could use the same method to speak to an HTML
server, or one of many other protocols as well.
Sincerely,
Dan Farrell <[EMAIL PROTECTED]>
.
554 5.6.0 Message contains invalid header at ./proxyd-filter.pl line
283.
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