wrote in message
news:1180721150.042249.259220@q69g2000hsb.googlegr oups.com...
> Recently I created a home-made SMTP server for fun/academic purposes.
> But lately I've become somewhat confused about the concept of "open-
> relay" mail servers. Apparently, open-relay mail servers are
> generally a *bad* thing, because spammers can just hijack them and use
> them for illicit purposes. Therefore, open-relay mail servers are
> strongly discouraged.
>
> But I'm a bit confused as to what an open-relay server actually is.
> My understanding is that a non-open relay server will only allow mail
> to be sent that is either FROM or TO a local user - whereas, an open-
> relay server will try to deliver any message to anyone. Is my
> understanding correct?
>

That is correct. When running an SMTP server, you want to make sure that
outgoing mail (not destined for your internal domains) comes from a set IP
block that you trust, or that that sending user is authenticated. The idea
is that you don't want me (or someone else you don't know) using your email
server to send mail to domains that you don't host.

Hope that helps,

Jim

On Jun 1, 3:05 pm, "Scooby" wrote:
> wrote in message
>
> news:1180721150.042249.259220@q69g2000hsb.googlegr oups.com...
>
> > Recently I created a home-made SMTP server for fun/academic purposes.
> > But lately I've become somewhat confused about the concept of "open-
> > relay" mail servers. Apparently, open-relay mail servers are
> > generally a *bad* thing, because spammers can just hijack them and use
> > them for illicit purposes. Therefore, open-relay mail servers are
> > strongly discouraged.
>
> > But I'm a bit confused as to what an open-relay server actually is.
> > My understanding is that a non-open relay server will only allow mail
> > to be sent that is either FROM or TO a local user - whereas, an open-
> > relay server will try to deliver any message to anyone. Is my
> > understanding correct?
>
> That is correct. When running an SMTP server, you want to make sure that
> outgoing mail (not destined for your internal domains) comes from a set IP
> block that you trust, or that that sending user is authenticated. The idea
> is that you don't want me (or someone else you don't know) using your email
> server to send mail to domains that you don't host.
>
> Hope that helps,
>
> Jim

Okay, I see. Thanks.