Open Relay SMTP - TCP-IP

This is a discussion on Open Relay SMTP - TCP-IP ; 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 ...

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Thread: Open Relay SMTP

  1. Open Relay SMTP

    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?


  2. Re: Open Relay SMTP

    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



  3. Re: Open Relay SMTP

    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.


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