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Relaying to SPF protected server

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  • J.R.Ewing
    Hello people, Iam trying to solv a problem with relaying. I want to setup a distribution list for one domain, where will postfix only relay email for
    Message 1 of 16 , Apr 1, 2010
      Hello people,

      Iam trying to solv a problem with relaying. I want to setup a
      distribution list for one domain, where will postfix only relay email
      for mydomain.com to selected users email addresses. No local mailboxes,
      only realaying list. Its quite simple, but.. but if I try to relay email
      comming from SPF active (has active SPF in DNS) server and it is relayed
      to SPF protected server (checking validity of sending server if SPF is
      present in DNS for the sending domain), it is rejected, because of
      course my server is not valid sending server for that domain.
      Is there any solution?
      I have idea to move senders address to "reply to" field and write new
      sender. Is it possible with postfix?

      Thanks

      J.R.
    • Ralf Hildebrandt
      ... Yes, SRS -- Ralf Hildebrandt Geschäftsbereich IT | Abteilung Netzwerk Charité - Universitätsmedizin Berlin Campus Benjamin Franklin Hindenburgdamm 30 |
      Message 2 of 16 , Apr 1, 2010
        * J.R.Ewing <jr.ewing@...>:
        > Hello people,
        >
        > Iam trying to solv a problem with relaying. I want to setup a
        > distribution list for one domain, where will postfix only relay email
        > for mydomain.com to selected users email addresses. No local
        > mailboxes, only realaying list. Its quite simple, but.. but if I try
        > to relay email comming from SPF active (has active SPF in DNS) server
        > and it is relayed to SPF protected server (checking validity of
        > sending server if SPF is present in DNS for the sending domain), it
        > is rejected, because of course my server is not valid sending server
        > for that domain.
        > Is there any solution?

        Yes, SRS
        --
        Ralf Hildebrandt
        Geschäftsbereich IT | Abteilung Netzwerk
        Charité - Universitätsmedizin Berlin
        Campus Benjamin Franklin
        Hindenburgdamm 30 | D-12203 Berlin
        Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
        ralf.hildebrandt@... | http://www.charite.de
      • Ralf Hildebrandt
        ... http://en.wikipedia.org/wiki/Sender_Rewriting_Scheme -- Ralf Hildebrandt Geschäftsbereich IT | Abteilung Netzwerk Charité - Universitätsmedizin Berlin
        Message 3 of 16 , Apr 1, 2010
          * Ralf Hildebrandt <Ralf.Hildebrandt@...>:

          > Yes, SRS

          http://en.wikipedia.org/wiki/Sender_Rewriting_Scheme

          --
          Ralf Hildebrandt
          Geschäftsbereich IT | Abteilung Netzwerk
          Charité - Universitätsmedizin Berlin
          Campus Benjamin Franklin
          Hindenburgdamm 30 | D-12203 Berlin
          Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
          ralf.hildebrandt@... | http://www.charite.de
        • Simon Waters
          ... As Ralph says SRS will do this. However I looked at this recently for a project, where I thought I d need SRS, and after reviewing the various issues and
          Message 4 of 16 , Apr 1, 2010
            On Thursday 01 April 2010 12:38:29 J.R.Ewing wrote:
            >
            > Is there any solution?
            > I have idea to move senders address to "reply to" field and write new
            > sender. Is it possible with postfix?

            As Ralph says SRS will do this.

            However I looked at this recently for a project, where I thought I'd need SRS,
            and after reviewing the various issues and SPF adoption figures, concluded
            I'd ignore SPF.

            In particular very few people reject outright on SPF failure (not least this
            isn't a good strategy compared to other filtering methods if all you want to
            do is reduce spam). Various systems handle SPF failed email in a more
            suspicious manner, but that isn't a practical problem in my experience.

            SRS might work better for your purpose, but SPF is broken by design and you
            should flag that to the people using it.

            We forward a lot of email, we don't do envelope rewriting, and have had a
            handful of complaints over the years, most from the same person who didn't
            seem to understand "we have no plans to change at this time".
          • Larry Stone
            ... One day is pretty short. The default is five days. Although things are a lot more reliable these days, it s still possible for an unattended destination
            Message 5 of 16 , Apr 1, 2010
              On 3/31/10 11:03 PM, Vernon A. Fort at vfort@... wrote:


              > The maximal_queue_lifetime-30s was for testing only - its normally set
              > for 1d.

              One day is pretty short. The default is five days. Although things are a lot
              more reliable these days, it's still possible for an unattended destination
              server to be down over a weekend or be down for long periods for an upgrade,
              etc.

              --
              Larry Stone
              lstone19@...
              http://www.stonejongleux.com/
            • J.R.Ewing
              ... Thanks Simon and Ralf for replies, I was observing SRS and it lookslike there is not a simple way to implement it with postfix. Because Iam just starting
              Message 6 of 16 , Apr 1, 2010
                Simon Waters napsal(a):
                > On Thursday 01 April 2010 12:38:29 J.R.Ewing wrote:
                >> Is there any solution?
                >> I have idea to move senders address to "reply to" field and write new
                >> sender. Is it possible with postfix?
                >
                > As Ralph says SRS will do this.
                >
                > However I looked at this recently for a project, where I thought I'd need SRS,
                > and after reviewing the various issues and SPF adoption figures, concluded
                > I'd ignore SPF.
                >
                > In particular very few people reject outright on SPF failure (not least this
                > isn't a good strategy compared to other filtering methods if all you want to
                > do is reduce spam). Various systems handle SPF failed email in a more
                > suspicious manner, but that isn't a practical problem in my experience.
                >
                > SRS might work better for your purpose, but SPF is broken by design and you
                > should flag that to the people using it.
                >
                > We forward a lot of email, we don't do envelope rewriting, and have had a
                > handful of complaints over the years, most from the same person who didn't
                > seem to understand "we have no plans to change at this time".


                Thanks Simon and Ralf for replies,

                I was observing SRS and it lookslike there is not a simple way to
                implement it with postfix.
                Because Iam just starting to relaying at my server, I will let some time
                to see, if there are some major problems with it or if it works
                unnoticed for users. Sad is, that the major freemail provider
                (seznam.cz) here in Czech Republic sadly implement and enforce SPF, the
                question is, how many domains that our users would be recieving from are
                SPF "protected" (I know only one, at domain of our company :-/).

                Thanks again

                J.R
              • Wietse Venema
                ... make that: local.unix (the connection type comes last).
                Message 7 of 16 , Apr 1, 2010
                  Wietse Venema:
                  > Vernon A. Fort:
                  > > The maximal_queue_lifetime-30s was for testing only - its normally set
                  > > for 1d. The sole issues is to prevent mail from bouncing back if we
                  > > don't get the encrypted volume mounted and cyrus started back up soon
                  > > enough. A reasonable example would be if the server rebooted due to a
                  > > power hiccup and we did not get the notifications quick enough.
                  > >
                  > > For now, i have a startup script to set the maximal_queue_lifetime to 1w
                  > > using postconf -e. This seems to do the trick.
                  >
                  > Another option is
                  >
                  > postconf -e "master_service_disable = unix.local"

                  make that: local.unix (the connection type comes last).

                  > Or even:
                  >
                  > postconf -e "master_service_disable = qmgr.fifo"
                  >
                  > (requires Postfix 2.6 or later).
                  >
                  > Wietse
                  >
                  >
                • ram
                  ... SPF if not the only reason why you would need SRS. We provide SMTP relay for various mail servers. I want to make sure that every customer uses only his
                  Message 8 of 16 , Apr 2, 2010
                    On Thu, 2010-04-01 at 12:14 +0000, Simon Waters wrote:
                    > On Thursday 01 April 2010 12:38:29 J.R.Ewing wrote:
                    > >
                    > > Is there any solution?
                    > > I have idea to move senders address to "reply to" field and write new
                    > > sender. Is it possible with postfix?
                    >
                    > As Ralph says SRS will do this.
                    >
                    > However I looked at this recently for a project, where I thought I'd need SRS,
                    > and after reviewing the various issues and SPF adoption figures, concluded
                    > I'd ignore SPF.
                    >
                    > In particular very few people reject outright on SPF failure (not least this
                    > isn't a good strategy compared to other filtering methods if all you want to
                    > do is reduce spam). Various systems handle SPF failed email in a more
                    > suspicious manner, but that isn't a practical problem in my experience.
                    >
                    > SRS might work better for your purpose, but SPF is broken by design and you
                    > should flag that to the people using it.
                    >
                    > We forward a lot of email, we don't do envelope rewriting, and have had a
                    > handful of complaints over the years, most from the same person who didn't
                    > seem to understand "we have no plans to change at this time".

                    SPF if not the only reason why you would need SRS.
                    We provide SMTP relay for various mail servers.
                    I want to make sure that every customer uses only his domain(s) and
                    sends the mail. Important to implement proper usage reporting as well as
                    stop abuse of network



                    Thanks
                    Ram





                    PS: SPF is used by gmail,hotmail, aol and 40% of the fortune 500
                    companies in the world among a huge lot of others. I dont think it
                    makes any sense to flag anything like "SPF is broken" to so many people.
                    Anyway discussing rising SPF adoption and the unreasonable arguments
                    against SPF is OT on the postfix mailing list.
                  • Wietse Venema
                    ... Postfix supports DKIM, DomainKeys, SPF, SRS, SenderID, etc., etc., via Milter plugins or SMTP-based content filters. Wietse
                    Message 9 of 16 , Apr 2, 2010
                      ram:
                      >
                      > On Thu, 2010-04-01 at 12:14 +0000, Simon Waters wrote:
                      > > On Thursday 01 April 2010 12:38:29 J.R.Ewing wrote:
                      > > >
                      > > > Is there any solution?
                      > > > I have idea to move senders address to "reply to" field and write new
                      > > > sender. Is it possible with postfix?

                      Postfix supports DKIM, DomainKeys, SPF, SRS, SenderID, etc., etc.,
                      via Milter plugins or SMTP-based content filters.

                      Wietse
                    • Jose Ildefonso Camargo Tolosa
                      Hi! This is getting interesting..... How, exactly, does mailman (or other mailing list manager) handles this? I mean, I have seen several SPF-enabled domains,
                      Message 10 of 16 , Apr 3, 2010
                        Hi!

                        This is getting interesting..... How, exactly, does mailman (or other
                        mailing list manager) handles this? I mean, I have seen several
                        SPF-enabled domains, and these domains have subscriptions to one or
                        more lists... now, reading the headers for one of the messages of this
                        lists, I got this:

                        Sender: owner-postfix-users@...

                        So... my guess is that the SPF check will go against this mail
                        address, not the one on the From field..... am I right?

                        What do you think?

                        lldefonso Camargo
                      • Sahil Tandon
                        ... SPF is against the ENVELOPE, not the HEADER. -- Sahil Tandon
                        Message 11 of 16 , Apr 3, 2010
                          On Sat, 03 Apr 2010, Jose Ildefonso Camargo Tolosa wrote:

                          > So... my guess is that the SPF check will go against this mail
                          > address, not the one on the From field..... am I right?

                          SPF is against the ENVELOPE, not the HEADER.

                          --
                          Sahil Tandon <sahil@...>
                        • Wietse Venema
                          ... SPF uses the address in MAIL FROM command. This is sent before the RCPT TO command and before the message header/body. Wietse
                          Message 12 of 16 , Apr 3, 2010
                            Jose Ildefonso Camargo Tolosa:
                            > Hi!
                            >
                            > This is getting interesting..... How, exactly, does mailman (or other
                            > mailing list manager) handles this? I mean, I have seen several
                            > SPF-enabled domains, and these domains have subscriptions to one or
                            > more lists... now, reading the headers for one of the messages of this
                            > lists, I got this:
                            >
                            > Sender: owner-postfix-users@...
                            >
                            > So... my guess is that the SPF check will go against this mail
                            > address, not the one on the From field..... am I right?
                            >
                            > What do you think?

                            SPF uses the address in MAIL FROM command. This is sent before
                            the RCPT TO command and before the message header/body.

                            Wietse
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