[CentOS] Sending Email Via Telnet

John Reddy linuxpencil at hotmail.com
Tue Oct 16 13:46:45 EDT 2012





> >    netstat -pant|grep ":25"|grep LISTEN
> > to see if any program is listening... output should look like:
> >   tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN 21493/sendmail
> >
> > guess it'll say 'postfix' or 'master' instead of 'sendmail' on RH6.

]# netstat -pant|grep ":25"|grep LISTEN
tcp        0      0 209.216.9.56:25             0.0.0.0:*                   LISTEN      14058/master
tcp        0      0 127.0.0.1:25                0.0.0.0:*                   LISTEN      14058/master

> 
> How long are you waiting for a response to appear?  Mailers do an
> assortment of reverse-dns lookups and perhaps an ident query to the
> source before responding.   If you firewall these with a 'drop'
> instead of 'reject' you leave the application hanging for fairly long
> timeout.  And some mailers have a config option for an intentional
> delay before their first message and will drop the connection it the
> other end sends first (snmp protocol requires the connecting host to
> wait).    Also, you should have something showing up in
> /var/log/mailllog about the connections.

I can't find anything in there that corresponds to the attempt to send an email. And why would I when there is no communication from the server in my telnet session? The problem appears to be in telnet, not in postfix. Again, this is one of 3 examples of my telnet sessions from 2 emails ago:

[root at mydomain john]# telnet 127.0.0.1 25
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
HELO justtesting
MAIL FROM: testing at gmail.com
RCPT TO: testing at gmail.com
DATA
To: testing at gmail.com
From: testing at gmail.com
Subject: testing
Date: Tu, Oct 2012 10:21:11 -0500
Testing
.
QUIT

Then it hangs. I never get back to a command prompt. There is never any interaction with the telnet program after the initial response. How do I trouble-shoot this?
TIA,
John

 		 	   		  


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