Sendmail Question

Ow Mun Heng Ow.Mun.Heng at
Mon May 17 20:23:26 UTC 2004

On Sun, 2004-05-16 at 05:40, Cowles, Steve wrote:
> Ow Mun Heng wrote:
> > Is this correct behaviour? I thought that to send emails you need to
> > either be authenticated (SMTP auth) or be on the same IPs as your
> > ISP?? 
> > 
> > Or is this what's happening? Sendmail is actually querying DNS root
> > servers and then upon getting the MX server, it connects straight to
> > port 25 of that MX Server and sends it? If that's the case, what's
> > stopping it from being a relay???
> > 
> > /curious
> By default, redhat configures sendmail (actually to only accept
> smtp requests from localhost. You would have to override that setting to
> have sendmail accept smtp requests from other hosts on your LAN. The maillog
> entry prior to the one you posted should show where the e-mail in question
> was submitted from. Based on your post where you stated you have NOT
> modified, I'd be willing to bet it was submitted from localhost.
> Take a look!
> As for your concern about being an open-relay... even if you were to modify
> and allow sendmail to accept smtp connections from another host

Nope. I'm not concerned about being an open relay. I know i"m not. I'm
just curious on how mails gets sent to the recipients. Alexander posted
a longish answer to that. Still digesting it, but I think I sort of
understand how things flow.

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