Earthlink SMTP (was Re: [TriLUG] kmail cannot send mail)

[Jeremy Portzer]

On Thu, 19 Sep 2002, Mike Mueller wrote:

> I was wondering about "mclean" and sometimes "barry".  I tried to fake
> them out by using smtp.bogus.com and I couldn't get connected.  It seems
> that I have to use a real smtp server.  The second time I tried to use
> smtp.oreilly.com I got busted with a message about not allowing
> relaying.  Did smtp.oreilly.com get wise the second time?  Does this
> "transparent proxy"  participate in the protocol enchange somehow?  Is
> there a logging option I can use to watch the exchange?  I could get out
> Ethereal and capture the exchange too.

You can just telnet to port 25 and see for yourself whether you're 
connecting to the real server or the proxy.  SMTP is a very simple 
plaintext protocol.  See 
http://www.siscom.net/~welter/professional/smtp.html for a sample list 
(there are numerous others).  All you need to know are HELO, MAIL FROM, 
RCPT TO, and DATA.  (Usually it will tell you after "RCPT TO" whether 
relaying is allowed.)

--Jeremy