sendmail

[Barry Brimer]

This server *may* be set up as an open relay, but that does not mean that it is.
 An open relay allows anyone and everyone the ability to relay mail.  So far,
all we know is that someone from a trusted IP address (such as localhost) is
able to deliver mail to a non-local domain, which itself indicates that it is
willing to relay mail for the IP address that connected to it, but does not
make it an open relay.  In a default RHEL 5 sendmail configuration the server
only listens on localhost to begin with, and the contents of the default
/etc/mail/access explicitly allow relaying from localhost.

Quoting "Marti, Rob" <RJM002 at shsu.edu>:

> She's set up as one, and the box is open to the internet (since it relayed
> mail to gmail).  It may not accept connections from outside the server/local
> network, but it is still an open relay.
>
> Rob Marti
> Systems Administrator
> Sam Houston State University
> 936-294-3804 // rjm002 at shsu.edu
>
>
> -----Original Message-----
> From: redhat-list-bounces at redhat.com [mailto:redhat-list-bounces at redhat.com]
> On Behalf Of Barry Brimer
> Sent: Wednesday, September 03, 2008 9:48 AM
> To: General Red Hat Linux discussion list
> Subject: RE: sendmail
>
> He telnetted to 127.0.0.1 25 .. which does not make him an open relay.
>
> Quoting "Marti, Rob" <RJM002 at shsu.edu>:
>
> > You're connecting from somewhere other than gmail.com and saying the mail
> is
> > coming from gmail.com.  You're trying to relay mail without authenticating,
> > which I would bet google has disabled.  Your MTA A is currently set up as
> an
> > open relay (unless you're at gmail.com).  Read
> > http://en.wikipedia.org/wiki/Open_mail_relay to see why this is bad.
> >
> > Rob Marti
> >
> > -----Original Message-----
> > From: redhat-list-bounces at redhat.com
> [mailto:redhat-list-bounces at redhat.com]
> > On Behalf Of Joy Methew
> > Sent: Wednesday, September 03, 2008 9:11 AM
> > To: General Red Hat Linux discussion list
> > Subject: sendmail
> >
> > here is two systems both are "mta" A and B with sendmail.
> > A is mine and B is gmail mat.
> > when i telnet my mta means A --->>telnet 127.0.0.1 25
> > helo hi
> > mail from:root at yahoo.com <from%3Aroot at yahoo.com>
> > rcpt to:ml4joy at gmail.com <to%3Aml4joy at gmail.com>
> > i recived mail very easly.
> > it means my mta "A" telnet indirectaly to gmail mta.
> > but when i try to telnet directly to gmail mta its give error like.
> >
> >
> > 220 mx.google.com ESMTP t26si1434066ele.4
> > helo gmail.com
> > 250 mx.google.com at your service
> > mail from:ml4joy at gmail.com <from%3Aml4joy at gmail.com>
> > 555 5.5.2 Syntax error t26si1434066ele.4
> >
> > Any idea why the "Syntax error".?
> >
> > Thanks
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