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Backing up indefinitely or for set time

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  • Brendan Grossman
    Hello I ve been told (not sure with postfix) that backup MXs can be configured to hold mail indefinitely or for a certain time period. Is this possible with
    Message 1 of 9 , Mar 1, 2006
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      Hello

      I've been told (not sure with postfix) that backup MXs can be configured to
      hold mail indefinitely or for a certain time period.

      Is this possible with postfix? The only option I've seen to configure a
      backup MX is with 'relay_domains domain.com' set on the backup MX of
      domain.com - which, I assume, instead of the sender's mail server attempting
      to redeliver, the backup MX will.

      As a matter of fact I'm not quite clear on how backup MXs work. If the above
      is correct, and the primary MX doesn't come back in x number of hours, will
      mail be bounced? And if so, will the sender's mail server attempt to
      redeliver or just return it to the sender?

      Thanks

      Brendan
    • Simon Waters
      ... They can do whatever you want. However indefinitely would be a bad idea, as people would never know if mail wasn t delivered. ... Yes ... Pretty much the
      Message 2 of 9 , Mar 1, 2006
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        On Wednesday 01 Mar 2006 09:53, Brendan Grossman wrote:
        >
        > I've been told (not sure with postfix) that backup MXs can be configured to
        > hold mail indefinitely or for a certain time period.

        They can do whatever you want. However indefinitely would be a bad idea, as
        people would never know if mail wasn't delivered.

        > Is this possible with postfix?

        Yes

        > The only option I've seen to configure a
        > backup MX is with 'relay_domains domain.com' set on the backup MX of
        > domain.com - which, I assume, instead of the sender's mail server
        > attempting to redeliver, the backup MX will.

        Pretty much the idea.

        > As a matter of fact I'm not quite clear on how backup MXs work. If the
        > above is correct, and the primary MX doesn't come back in x number of
        > hours, will mail be bounced?

        Yes.

        If you aren't clear how backup MX work, I'd strongly suggest not having one.
        They made sense when Internet email was more gentlemanly, and connectivity
        was a more hit and miss affair than it is today, and email was a substantial
        part of ones bandwidth. When you would make sure your email got somewhere you
        could reliably talk to, and ideally talk to cheaply.

        Now it is more sensible for people to keep the configuration as simple as
        possible, and let the senders server retry as long and as often as it likes
        (or not).

        The main use for extra MX records these days it to load balance across
        multiple identical mail servers - and we don't have enough email to justify
        that complexity here - ymmv.

        > And if so, will the sender's mail server
        > attempt to redeliver or just return it to the sender?

        It will return it to sender.
      • Brendan Grossman
        ... It may be justifiable in my case. I have a postfix gateway that relays mail for internal UNIX clients. When the clients are shutdown at night or for even
        Message 3 of 9 , Mar 1, 2006
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          > > I've been told (not sure with postfix) that backup MXs can be
          > > configured to hold mail indefinitely or for a certain time period.
          >
          > They can do whatever you want. However indefinitely would be
          > a bad idea, as people would never know if mail wasn't delivered.

          It may be justifiable in my case. I have a postfix gateway that relays mail
          for internal UNIX clients. When the clients are shutdown at night or for
          even days (could even be weeks, if the user goes on on holidays etc), I'd
          like my gateway to hold their mail.

          Instead of local delivery, I could give them accounts and allow POP access
          or something on the gateway, but if each client has an MTA, they may as well
          use it?

          To make matters worse, the internet connection for this network has a
          dynamic IP, so when the IP changes, I need to ensure mail doesn't bounce. I
          do have a script that updates DNS, but even though it's reasonably reliable,
          I'd still like a fallback solution.

          > > Is this possible with postfix?
          >
          > Yes

          How so? I can't find any info.

          > > As a matter of fact I'm not quite clear on how backup MXs
          > work. If the
          > > above is correct, and the primary MX doesn't come back in x
          > number of
          > > hours, will mail be bounced?
          >
          > Yes.
          >
          > If you aren't clear how backup MX work, I'd strongly suggest
          > not having one.

          I'd like to become "clear", so that I can :) Unless you can think of other
          ways to ensure mail doesn't bounce for said configuration.
        • Simon Waters
          ... Don t use boxes as SMTP servers if they aren t highly available - you ll just create a headache for yourself. Imagine I sent an email, you ll hold it
          Message 4 of 9 , Mar 1, 2006
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            On Wednesday 01 Mar 2006 11:15, Brendan Grossman wrote:
            >
            > It may be justifiable in my case. I have a postfix gateway that relays mail
            > for internal UNIX clients. When the clients are shutdown at night or for
            > even days (could even be weeks, if the user goes on on holidays etc), I'd
            > like my gateway to hold their mail.

            Don't use boxes as SMTP servers if they aren't highly available - you'll just
            create a headache for yourself.

            Imagine I sent an email, you'll hold it indefinitely - if the person never
            switches on their box, I'll never know it was never received.

            > Instead of local delivery, I could give them accounts and allow POP access
            > or something on the gateway, but if each client has an MTA, they may as
            > well use it?

            I'd lose the unnecessary services and install POP3 or IMAP4 on a central
            server in a jiffy. Do not needlessly multiply SMTP servers.

            > To make matters worse, the internet connection for this network has a
            > dynamic IP, so when the IP changes, I need to ensure mail doesn't bounce. I
            > do have a script that updates DNS, but even though it's reasonably
            > reliable, I'd still like a fallback solution.

            Don't put an SMTP server on a dynamic IP address - you'll only create a
            headache for yourself. If you've enough boxes to be worrying about such
            things get a static IP address, it will be less work than trying to work
            around it.
          • Keith Matthews
            On Wed, 1 Mar 2006 11:45:49 +0000 ... I ll add to that - If your ISP won t provide one then change ISP. In my experience ISPs that insist on dynamic IP only
            Message 5 of 9 , Mar 1, 2006
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              On Wed, 1 Mar 2006 11:45:49 +0000
              Simon Waters <simonw@...> wrote:


              > Don't put an SMTP server on a dynamic IP address - you'll only create
              > a headache for yourself. If you've enough boxes to be worrying about
              > such things get a static IP address, it will be less work than trying
              > to work around it.



              I'll add to that - If your ISP won't provide one then change ISP. In my
              experience ISPs that insist on dynamic IP only don't want servers on
              their systems and won't provide proper support.

              --
              Due to excessive spam as a result of archiving of this list I only
              accept mail through the list server.
            • Brian Collins
              ... That is correct. Speaking from the standpoint of an ISP, we provide static IPs to those that request them for doing things like this. Still, other than
              Message 6 of 9 , Mar 1, 2006
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                > > Don't put an SMTP server on a dynamic IP address - you'll only create
                > > a headache for yourself. If you've enough boxes to be worrying about
                > > such things get a static IP address, it will be less work than trying
                > > to work around it.
                >
                >
                >
                > I'll add to that - If your ISP won't provide one then change ISP. In my
                > experience ISPs that insist on dynamic IP only don't want servers on
                > their systems and won't provide proper support.

                That is correct. Speaking from the standpoint of an ISP, we provide static
                IPs to those that request them for doing things like this. Still, other
                than how to avoid being an open relay, we do not offer much support (as in,
                how they should configure their (mail|web|other) server. We also don't
                offer a lot of sympathy to the ones who become open relays or get themselves
                blacklisted because they wanted to send spam and found our SMTP servers
                not-very-conducive to that.

                --Brian
              • Brendan Grossman
                ... Unfortunately, the difference between a static and dynamic IP for me here in Australia, is a loss of 7mbps off my connection, or, an extra $80+ per month.
                Message 7 of 9 , Mar 1, 2006
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                  > > > Don't put an SMTP server on a dynamic IP address - you'll only
                  > > > create a headache for yourself. If you've enough boxes to be
                  > > > worrying about such things get a static IP address, it
                  > will be less
                  > > > work than trying to work around it.
                  > >
                  > >
                  > >
                  > > I'll add to that - If your ISP won't provide one then
                  > change ISP. In
                  > > my experience ISPs that insist on dynamic IP only don't
                  > want servers
                  > > on their systems and won't provide proper support.
                  >
                  > That is correct. Speaking from the standpoint of an ISP, we
                  > provide static IPs to those that request them for doing
                  > things like this. Still, other than how to avoid being an
                  > open relay, we do not offer much support (as in, how they
                  > should configure their (mail|web|other) server. We also
                  > don't offer a lot of sympathy to the ones who become open
                  > relays or get themselves blacklisted because they wanted to
                  > send spam and found our SMTP servers not-very-conducive to that.

                  Unfortunately, the difference between a static and dynamic IP for me here in
                  Australia, is a loss of 7mbps off my connection, or, an extra $80+ per
                  month. I have ADSL2+ (cable's unavailable) and the only static IP plans I've
                  found are "business" plans, and they're usually over $100 per month.

                  Sure, having a static IP makes things easier, but I have a script that
                  checks my IP every hour and if it's changed, updates it. So there's probably
                  not a huge difference, just a static IP would give me peace of mind and
                  would ensure unless the connection were to go down, mail would never bounce.
                • Matt Fretwell
                  On Wed, 1 Mar 2006 23:28:46 +1030 ... Generally, it is a case of getting one of the business grade services. You will lose downlink speed on the basic business
                  Message 8 of 9 , Mar 1, 2006
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                    On Wed, 1 Mar 2006 23:28:46 +1030
                    "Brendan Grossman" <brendan@...> wrote:


                    > Unfortunately, the difference between a static and dynamic IP
                    > for me here in Australia, is a loss of 7mbps off my
                    > connection, or, an extra $80+ per month. I have ADSL2+
                    > (cable's unavailable) and the only static IP plans I've found
                    > are "business" plans, and they're usually over $100 per month.
                    >
                    > Sure, having a static IP makes things easier, but I have a
                    > script that checks my IP every hour and if it's changed,
                    > updates it. So there's probably not a huge difference, just a
                    > static IP would give me peace of mind and would ensure unless
                    > the connection were to go down, mail would never bounce.

                    Generally, it is a case of getting one of the business grade
                    services. You will lose downlink speed on the basic business
                    service, or get charged disproportionately for a faster link,
                    but if you are running a mailserver on this link, it is a case
                    of either suck in the extra cost and run a mailserver that will
                    get your mail to its final destination, or run the risk of being
                    blocked by various external MTA's if you stay as you are.
                    Granted, the price does seem steep, but you do also get extra
                    benefits that a consumer grade connection will not.

                    There are many of us who would like to pay less, but
                    the reliabilty, (outgoing as well as receiving), makes a static
                    IP setup practically a must if you value your e-mail service.


                    Matt
                  • Keith Matthews
                    On Wed, 1 Mar 2006 07:46:32 -0500 ... If you offer anything at all to people operating servers you re doing better than most of the big players I have to deal
                    Message 9 of 9 , Mar 1, 2006
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                      On Wed, 1 Mar 2006 07:46:32 -0500
                      "Brian Collins" <listbc@...> wrote:

                      > > > Don't put an SMTP server on a dynamic IP address - you'll only
                      > > > create a headache for yourself. If you've enough boxes to be
                      > > > worrying about such things get a static IP address, it will be
                      > > > less work than trying to work around it.
                      > >
                      > >
                      > >
                      > > I'll add to that - If your ISP won't provide one then change ISP. In
                      > > my experience ISPs that insist on dynamic IP only don't want servers
                      > > on their systems and won't provide proper support.
                      >
                      > That is correct. Speaking from the standpoint of an ISP, we provide
                      > static IPs to those that request them for doing things like this.
                      > Still, other than how to avoid being an open relay, we do not offer
                      > much support .

                      If you offer anything at all to people operating servers you're doing
                      better than most of the big players I have to deal with. BT especially -
                      all you can get out of their trained monkey types is reading from a
                      script on how to set up Outlook and no deviations. (Yes I know BT runs
                      it's call centre from India these days, and I have no beef with the
                      people or their accents, it's the lack of training and inability to
                      refer the problem to those who are better trained that gripes me).

                      --
                      Due to excessive spam as a result of archiving of this list I only
                      accept mail through the list server.
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