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Re: Another SPAM doubt

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  • Michael Katz
    There are many antispam solutions for Postfix that are not Amavis based. Amavis relies on SpamAssassin, one of the slowest spam analysis engines that comes
    Message 1 of 19 , Dec 1, 2005
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      There are many antispam solutions for Postfix that are not Amavis
      based. Amavis relies on SpamAssassin, one of the slowest spam analysis
      engines that comes with a huge administrative burden for certain (not
      all) installations. SA/Amavis is clearly the most widely deployed
      solution on this mailing list, but there is another world that exists
      outside of the mailing list and there are many options that integrate
      with Postfix that are more accurate, require less administration and
      will perform better. Don't forget about the great SMTP level facilities
      that Postfix provides as well, which are well documented on the list.

      M Katz


      Sergio Ferreira wrote:

      >Hi List,
      >
      >I still setting SPAM stuffs at my setup, now I have one doubt about some
      >third parts tools. I have known about integration of Postfix and Clamav,
      >Spamassassim too, instead of Postfix + Clamav + Amavis + Spamassassin.
      >Anyone had experienced boths cases for help me with the advantages and the
      >disadvantages between them?
      >Without Amavis my server will be trustworth too? My question is about should
      >I use Amavis or not? Some people says It is more easy to manage these things
      >with Amavis, It is true?
      >
      >Any conserning will be very wellcome to make things more clear.
      >
      >
      >Thanks,
      >
      >Sergio
      >
      >
      >
      >
      >
      >
      >
    • mouss
      ... The first question is which filtering engine you want to use. some choices: - spamassassin. widely used. resource intensive. maintenance burden - dspam.
      Message 2 of 19 , Dec 1, 2005
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        Sergio Ferreira a écrit :
        > Hi List,
        >
        > I still setting SPAM stuffs at my setup, now I have one doubt about some
        > third parts tools. I have known about integration of Postfix and Clamav,
        > Spamassassim too, instead of Postfix + Clamav + Amavis + Spamassassin.
        > Anyone had experienced boths cases for help me with the advantages and the
        > disadvantages between them?
        > Without Amavis my server will be trustworth too? My question is about should
        > I use Amavis or not? Some people says It is more easy to manage these things
        > with Amavis, It is true?
        >
        > Any conserning will be very wellcome to make things more clear.
        >

        The first question is which filtering engine you want to use. some choices:

        - spamassassin. widely used. resource intensive. maintenance burden
        - dspam. bayesian (with some variants). doc is not very clear.
        - crm114, bogofilter, ....

        so there are a lot of choices. some people daisy chain multiple engines.


        amavisd-new:
        - good interface to spamassassin. no more fork per mail + works in
        gateway mode (so can filter relayed mail if you want)
        - can block bad attachments
        - compatible with many anti-virus solutions
        - support for policies ("policy banks")
      • Gordon Thagard
        ... list, but there is another world that exists outside of the mailing ... more accurate, require less administration and will perform better. Like What? I am
        Message 3 of 19 , Dec 1, 2005
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          >SA/Amavis is clearly the most widely deployed solution on this mailing
          list, but there is another world that exists outside of the mailing
          >list and there are many options that integrate with Postfix that are
          more accurate, require less administration and will perform better.

          Like What? I am starting to *hate* amavisd. I've been using it for two
          years now and its not unusual to have it just stop working after a
          holiday SPAM/Virus blitz. I'm having this problem right now and I
          haven't touched the config in many months - One machine hangs on the
          SMTP connection and another immediately looses the SMTP connection. I've
          been forced to disable amavis for a couple of days while I play around
          with possibilities. Its awful.

          Please share with the group one of these "more accurate, ... less
          administration and will perform better" solutions.

          Cheers,
        • Kelly Sauke
          ... How about some examples of these other options?
          Message 4 of 19 , Dec 1, 2005
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            Michael Katz wrote:

            > SA/Amavis is clearly the most widely deployed solution on this mailing
            > list, but there is another world that exists outside of the mailing
            > list and there are many options that integrate with Postfix that are
            > more accurate, require less administration and will perform better.


            How about some examples of these other options?
          • Chris St. Pierre
            We use Sophos PureMessage (not free), currently with Sun s JMS. We ll be moving to Postfix this summer, and taking PureMessage with us, as it integrates with
            Message 5 of 19 , Dec 1, 2005
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              We use Sophos PureMessage (not free), currently with Sun's JMS. We'll
              be moving to Postfix this summer, and taking PureMessage with us, as
              it integrates with Postfix. PureMessage is a joy to administer -- it
              includes both an easy web interface and a powerful CLI, very un*x-like
              behavior (i.e., well-documented, plain-text config files), and it's
              written mostly in Perl -- a plus for us, as we're pretty proficient in
              Perl here.

              The downside is cost, which is not inconsiderable. However, we looked
              at SpamAssassin and then at PureMessage and the decision was pretty
              easy.

              Chris St. Pierre
              Unix Systems Administrator
              Nebraska Wesleyan University

              On Thu, 1 Dec 2005, Kelly Sauke wrote:

              >Michael Katz wrote:
              >
              >> SA/Amavis is clearly the most widely deployed solution on this mailing
              >> list, but there is another world that exists outside of the mailing
              >> list and there are many options that integrate with Postfix that are
              >> more accurate, require less administration and will perform better.
              >
              >
              >How about some examples of these other options?
              >
            • Sergio Ferreira
              Hi Mouss, ... I was thinking about to use Spamassassin. It worth or just is the mostly used? ... This one I doesn´t heard about It, but when I see problems
              Message 6 of 19 , Dec 1, 2005
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                Hi Mouss,

                >>>>>> I still setting SPAM stuffs at my setup, now I have one
                >>>>>doubt about
                >>>>>> some third parts tools. I have known about integration
                >>>>>of Postfix and
                >>>>>> Clamav, Spamassassim too, instead of Postfix + Clamav +
                >>>>>Amavis + Spamassassin.
                >>>>>> Anyone had experienced boths cases for help me with the
                >>>>>advantages and
                >>>>>> the disadvantages between them?
                >>>>>> Without Amavis my server will be trustworth too? My
                >>>>>question is about
                >>>>>> should I use Amavis or not? Some people says It is more
                >>>>>easy to manage
                >>>>>> these things with Amavis, It is true?
                >>>>>>
                >>>>>> Any conserning will be very wellcome to make things more clear.
                >>>>>>
                >>>>>>
                >>>>>>
                >>>>>>
                >>>>>
                >>>>>The first question is which filtering engine you want to
                >>>>>use. some choices:
                >>>>>
                >>>>>- spamassassin. widely used. resource intensive. maintenance burden

                I was thinking about to use Spamassassin. It worth or just is the mostly
                used?




                >>>>>- dspam. bayesian (with some variants). doc is not very clear.

                This one I doesn´t heard about It, but when I see problems with
                documentation then I´d rather not even try. :-/



                >>>>>- crm114, bogofilter, ....

                Bogofilter... I read a little bit about, but I wasn´t able to choose for It.
                It´s similar to spamassassin? It is easy to setup and manage?

                >>>>>
                >>>>>so there are a lot of choices. some people daisy chain
                >>>>>multiple engines.

                Unless It is very recommended, I prefer only one engine. I belive It is easy
                to fix problems and administering :-)



                >>>>>
                >>>>>
                >>>>>amavisd-new:
                >>>>>- good interface to spamassassin. no more fork per mail +
                >>>>>works in gateway mode (so can filter relayed mail if you want)
                >>>>>- can block bad attachments
                >>>>>- compatible with many anti-virus solutions
                >>>>>- support for policies ("policy banks")

                It is well documented and easy to setup? I intending to adopt It.

                Bye,

                Sergio
              • Udo Rader
                ... remember: there are no slow applications, only inappropriate hardware (well, most of the time ;-) Not so long ago, the sysreqs for running a mail server
                Message 7 of 19 , Dec 1, 2005
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                  On Thu, 2005-12-01 at 09:14 -0500, Michael Katz wrote:
                  > There are many antispam solutions for Postfix that are not Amavis
                  > based. Amavis relies on SpamAssassin, one of the slowest spam analysis

                  remember: there are no slow applications, only inappropriate hardware
                  (well, most of the time ;-) Not so long ago, the sysreqs for running a
                  mail server very low compared to other services, but nowadays with all
                  the content filtering stuff you need really high performing machines.

                  > engines that comes with a huge administrative burden for certain (not

                  if that was a postfix related question, someone would surely say: prove
                  it.

                  Udo Rader

                  --
                  bestsolution.at EDV Systemhaus GmbH
                  http://www.bestsolution.at
                • Victor Duchovni
                  ... Money can buy you bandwidth, but latency is forever (John Mashey). More often these days you also need many separate machines, so that the latency of
                  Message 8 of 19 , Dec 1, 2005
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                    On Thu, Dec 01, 2005 at 05:53:21PM +0100, Udo Rader wrote:

                    > On Thu, 2005-12-01 at 09:14 -0500, Michael Katz wrote:
                    > > There are many antispam solutions for Postfix that are not Amavis
                    > > based. Amavis relies on SpamAssassin, one of the slowest spam analysis
                    >
                    > remember: there are no slow applications, only inappropriate hardware
                    > (well, most of the time ;-) Not so long ago, the sysreqs for running a
                    > mail server very low compared to other services, but nowadays with all
                    > the content filtering stuff you need really high performing machines.
                    >

                    Money can buy you bandwidth, but latency is forever (John Mashey).
                    More often these days you also need many separate machines, so that
                    the latency of various lookups can be amortized over many parallel
                    deliveries.

                    --
                    Viktor.

                    Disclaimer: off-list followups get on-list replies or get ignored.
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                  • Sergio Ferreira
                    Hi, Chris, ... I read about It too, seems to be a good one really. But, the Boss wants 100% free software solution. Therefore, if I propose It He gonna starts
                    Message 9 of 19 , Dec 1, 2005
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                      Hi, Chris,

                      >>>>>-----Original Message-----
                      >>>>>From: owner-postfix-users@...
                      >>>>>[mailto:owner-postfix-users@...] On Behalf Of
                      >>>>>Chris St. Pierre
                      >>>>>Sent: Thursday, December 01, 2005 2:47 PM
                      >>>>>To: Kelly Sauke
                      >>>>>Cc: postfix-users@...
                      >>>>>Subject: Re: Another SPAM doubt
                      >>>>>
                      >>>>>We use Sophos PureMessage (not free), currently with Sun's
                      >>>>>JMS. We'll be moving to Postfix this summer, and taking
                      >>>>>PureMessage with us, as it integrates with Postfix.
                      >>>>>PureMessage is a joy to administer -- it includes both an
                      >>>>>easy web interface and a powerful CLI, very un*x-like
                      >>>>>behavior (i.e., well-documented, plain-text config files),
                      >>>>>and it's written mostly in Perl -- a plus for us, as we're
                      >>>>>pretty proficient in Perl here.
                      >>>>>
                      >>>>>The downside is cost, which is not inconsiderable.
                      >>>>>However, we looked at SpamAssassin and then at PureMessage
                      >>>>>and the decision was pretty easy.
                      >>>>>
                      >>>>>Chris St. Pierre
                      >>>>>Unix Systems Administrator
                      >>>>>Nebraska Wesleyan University
                      >>>>>

                      I read about It too, seems to be a good one really. But, the Boss wants 100%
                      free software solution. Therefore, if I propose It He gonna starts to kill
                      me very slowly. :-)



                      >>>>>On Thu, 1 Dec 2005, Kelly Sauke wrote:
                      >>>>>
                      >>>>>>Michael Katz wrote:
                      >>>>>>
                      >>>>>>> SA/Amavis is clearly the most widely deployed solution on this
                      >>>>>>> mailing list, but there is another world that exists
                      >>>>>outside of the
                      >>>>>>> mailing list and there are many options that integrate
                      >>>>>with Postfix
                      >>>>>>> that are more accurate, require less administration and
                      >>>>>will perform better.
                      >>>>>>
                      >>>>>>
                      >>>>>>How about some examples of these other options?
                      >>>>>>

                      Thanks,

                      Sergio
                    • Michael Katz
                      Kelly Sauke wrote: Michael Katz wrote: SA/Amavis is clearly the most widely deployed solution on this mailing list, but there is another world that exists
                      Message 10 of 19 , Dec 1, 2005
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                        Kelly Sauke wrote:
                        Michael Katz wrote:
                        
                          
                        SA/Amavis is clearly the most widely deployed solution on this mailing
                        list, but there is another world that exists outside of the mailing
                        list and there are many options that integrate with Postfix that are
                        more accurate, require less administration and will perform better. 
                            
                        
                        How about some examples of these other options?
                          
                        I am biased, but I think that MPP is a great one, http://messagepartners.com, which support multiple spam engnes including Cloudmark, Mailshell and Spamassassin.   Sophos has one, which was mentioned,  Symantec, KAV, VirusBuster are a few others. 
                        
                          

                      • Jure Pečar
                        On Thu, 01 Dec 2005 09:11:10 -0600 ... I m currently playing with dspam, which can now in version 3.6 communicate with clamAV too. It s a bit of a black magic
                        Message 11 of 19 , Dec 1, 2005
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                          On Thu, 01 Dec 2005 09:11:10 -0600
                          Kelly Sauke <ksauke@...> wrote:

                          > How about some examples of these other options?

                          I'm currently playing with dspam, which can now in version 3.6 communicate
                          with clamAV too. It's a bit of a black magic and undeterministic
                          (statistics and all that ...), but can get very reliable for users'
                          specific mail patterns. Also 10x faster than Amavis/SA and once configured,
                          requires almost no administration.


                          --

                          Jure Pečar
                          http://jure.pecar.org/
                        • Covington, Chris
                          ... I d like to weigh in here. We used SpamAssassin/amavisd-new for about 2 or 3 years and the results were acceptable, the setup was fairly straightforward
                          Message 12 of 19 , Dec 1, 2005
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                            On Thu, Dec 01, 2005 at 10:45:54AM -0200, Sergio Ferreira wrote:
                            > Hi List,
                            >
                            > I still setting SPAM stuffs at my setup, now I have one doubt about some
                            > third parts tools. I have known about integration of Postfix and Clamav,
                            > Spamassassim too, instead of Postfix + Clamav + Amavis + Spamassassin.
                            > Anyone had experienced boths cases for help me with the advantages and the
                            > disadvantages between them?
                            > Without Amavis my server will be trustworth too? My question is about should
                            > I use Amavis or not? Some people says It is more easy to manage these things
                            > with Amavis, It is true?
                            >
                            > Any conserning will be very wellcome to make things more clear.

                            I'd like to weigh in here. We used SpamAssassin/amavisd-new for about 2
                            or 3 years and the results were acceptable, the setup was fairly
                            straightforward and the overhead was low. It's a good beginner's setup
                            that will take care of 90-95% of your spam problems. The problem with SA
                            (and most commercial products, but I digress) is primarily that it's a
                            one-size-fits-all solution, and secondarily: it assumes English as the
                            primary language of all spam, it has a lot network test latency, it
                            primarily adapts through new versions containing new rulesets, etc.
                            (For instance, with our population medicine, nutrition & health
                            enhancement are integral parts of every day business, not spam!)
                            Network tests help SA a little in this regard, but in many ways it's a
                            static system that waits for the next release to be more effective, and
                            its efficacy drops over time until the next version, etc.

                            In the last few months we've preserved amavisd-new to do virus scanning /
                            attachment blocking, removed SpamAssassin, and we've added DSPAM which
                            does the anti-spam. DSPAM is fairly difficult to setup and understand
                            (the documentation is sparse) but it's very effective and adaptive.
                            DSPAM is also more of a resource hog: we have a 400MB or so global MySQL
                            database compared to SA's small-footprint client installation. This
                            database contains 30,000 or so messages in the spam corpus and 40,000
                            or so in the ham corpus. The message scanning times are faster, but
                            the resources required are much higher. With all that said, it's an
                            excellent solution. It's highly accurate (we're at 98.87% right now,
                            this constantly gets better): The database is specially-tailored to
                            our users' email patterns, and our users continually update it themselves
                            by forwarding false positives and negatives to training addresses.
                            So if you have the patience, skills and hardware required to use
                            DSPAM, go for it!

                            ---
                            Chris Covington
                            IT
                            Plus One Health Management
                            75 Maiden Lane Suite 801
                            NY, NY 10038
                            646-312-6269
                            http://www.plusoneactive.com

                            !DSPAM:1,438f6162289285153766755!
                          • Jorey Bump
                            ... Maybe I m missing something, but a system that requires users to continue to handle spam (if not actually read it) *and* to learn another interface to
                            Message 13 of 19 , Dec 1, 2005
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                              Covington, Chris wrote:

                              > this constantly gets better): The database is specially-tailored to
                              > our users' email patterns, and our users continually update it themselves
                              > by forwarding false positives and negatives to training addresses.
                              > So if you have the patience, skills and hardware required to use
                              > DSPAM, go for it!

                              Maybe I'm missing something, but a system that requires users to
                              continue to handle spam (if not actually read it) *and* to learn another
                              interface to train the application seems like little more than a mail
                              sorting program to me.

                              I want to reject spam immediately, during the SMTP conversation. I'm
                              doing that now on a low-volume site, running SA in a before-queue
                              content filter using spampd. While it may be possible to do the same
                              with dspam, SA bootstraps its bayesian filter with a multitude of rules,
                              so no user intervention is required. For the little bit of spam that
                              gets through, I can run sa-learn, or, even better, add a local rule that
                              will improve the bayesian filter after a few rejections.
                            • Covington, Chris
                              ... You don t have to use DSPAM s quarantine interface. We use Exchange s Junk E-mail folder which is built-in: X-DSPAM-Result: Spam will move a message to
                              Message 14 of 19 , Dec 1, 2005
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                                On Thu, Dec 01, 2005 at 04:07:04PM -0500, Jorey Bump wrote:
                                > Covington, Chris wrote:
                                >
                                > >this constantly gets better): The database is specially-tailored to
                                > >our users' email patterns, and our users continually update it themselves
                                > >by forwarding false positives and negatives to training addresses.
                                > >So if you have the patience, skills and hardware required to use
                                > >DSPAM, go for it!
                                >
                                > Maybe I'm missing something, but a system that requires users to
                                > continue to handle spam (if not actually read it) *and* to learn another
                                > interface to train the application seems like little more than a mail
                                > sorting program to me.

                                You don't have to use DSPAM's quarantine interface. We use Exchange's
                                "Junk E-mail" folder which is built-in: X-DSPAM-Result: Spam will move
                                a message to this folder (and all X-DSPAM* headers are removed before
                                they hit the DSPAM servers so this can't be spoofed). The "Junk E-mail"
                                folder's contents are automatically expired after 30 days. This
                                requires Exchange event sinks, BTW. Users need to forward mistakes
                                to training addresses.

                                > I want to reject spam immediately, during the SMTP conversation. I'm
                                > doing that now on a low-volume site, running SA in a before-queue
                                > content filter using spampd. While it may be possible to do the same
                                > with dspam, SA bootstraps its bayesian filter with a multitude of rules,
                                > so no user intervention is required. For the little bit of spam that
                                > gets through, I can run sa-learn, or, even better, add a local rule that
                                > will improve the bayesian filter after a few rejections.

                                That might work for a smaller site, but it doesn't scale well and it
                                places the administrative burden on you.

                                ---
                                Chris Covington
                                IT
                                Plus One Health Management
                                75 Maiden Lane Suite 801
                                NY, NY 10038
                                646-312-6269
                                http://www.plusoneactive.com

                                !DSPAM:1,438f69b3289288246520239!
                              • Robert Felber
                                ... Out of curiousity, how does dspam handle multirecipient mail? ...
                                Message 15 of 19 , Dec 1, 2005
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                                  On Thu, Dec 01, 2005 at 04:07:04PM -0500, Jorey Bump wrote:
                                  > now on a low-volume site, running SA in a before-queue content filter using
                                  > spampd.

                                  Out of curiousity, how does dspam handle multirecipient mail?

                                  > RCPT TO:<foo@...>
                                  > RCPT TO:<foo2@...>
                                  < OK
                                  > DATA
                                  < OK
                                  > headers:
                                  >
                                  > body
                                  > .
                                  < 4xx|5xx

                                  What, if foo2 doesn't want to use dspam? In that case, he would lose the mail
                                  still. Or am I wrong?


                                  --
                                  Robert Felber (PGP: 896CF30B)
                                  Munich, Germany
                                • Jorey Bump
                                  ... I don t know about dspam, I m using SpamAssassin *globally* in a before-queue content filter. Yes, it rejects the entire message for all recipients, but
                                  Message 16 of 19 , Dec 1, 2005
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                                    Robert Felber wrote:
                                    > On Thu, Dec 01, 2005 at 04:07:04PM -0500, Jorey Bump wrote:
                                    >
                                    >>now on a low-volume site, running SA in a before-queue content filter using
                                    >>spampd.
                                    >
                                    >
                                    > Out of curiousity, how does dspam handle multirecipient mail?
                                    >
                                    >
                                    >>RCPT TO:<foo@...>
                                    >>RCPT TO:<foo2@...>
                                    >
                                    > < OK
                                    >
                                    >>DATA
                                    >
                                    > < OK
                                    >
                                    >>headers:
                                    >>
                                    >>body
                                    >>.
                                    >
                                    > < 4xx|5xx
                                    >
                                    > What, if foo2 doesn't want to use dspam? In that case, he would lose the mail
                                    > still. Or am I wrong?

                                    I don't know about dspam, I'm using SpamAssassin *globally* in a
                                    before-queue content filter. Yes, it rejects the entire message for all
                                    recipients, but that's the point. My users don't even know their mail is
                                    being filtered (and will complain about getting as many as 5-10 spam
                                    messages in a week!). I use a lot of different spam-fighting techniques,
                                    but *all* of them are apparent to the sender (rejections, no
                                    backscatter), so I will hear about any problems that occur (rare, but it
                                    does happen).

                                    I used to quarantine everything, inspect it, then pass on the ham, but
                                    that was a *true* administrative nightmare. This approach adds
                                    complexity to configuration, and lets me enjoy my vacations a little
                                    more. :)

                                    Don't overlook Chris' point about scalability, which cuts both ways. I'm
                                    not an ISP, and support most of my clients down to their desktops, so
                                    eliminating spam and viruses can save me support calls down the line.
                                    But in a large general purpose population, per-user spam categorization
                                    may be mandatory.
                                  • Covington, Chris
                                    ... One correction - we are not using per-user databases. It s a single per-company database that people can train on mistakes. ... Chris Covington IT Plus
                                    Message 17 of 19 , Dec 2, 2005
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                                      On Thu, Dec 01, 2005 at 05:46:38PM -0500, Jorey Bump wrote:
                                      > Don't overlook Chris' point about scalability, which cuts both ways. I'm
                                      > not an ISP, and support most of my clients down to their desktops, so
                                      > eliminating spam and viruses can save me support calls down the line.
                                      > But in a large general purpose population, per-user spam categorization
                                      > may be mandatory.

                                      One correction - we are not using per-user databases. It's a single
                                      per-company database that people can train on mistakes.

                                      ---
                                      Chris Covington
                                      IT
                                      Plus One Health Management
                                      75 Maiden Lane Suite 801
                                      NY, NY 10038
                                      646-312-6269
                                      http://www.plusoneactive.com
                                    • Covington, Chris
                                      ... No, DSPAM can be used as an LMTP content-filter, which supports per-user opt-in or opt-out enrollment. If foo@bar.com is opted-in, then that message will
                                      Message 18 of 19 , Dec 2, 2005
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                                        On Thu, Dec 01, 2005 at 11:11:06PM +0100, Robert Felber wrote:
                                        > On Thu, Dec 01, 2005 at 04:07:04PM -0500, Jorey Bump wrote:
                                        > > now on a low-volume site, running SA in a before-queue content filter using
                                        > > spampd.
                                        >
                                        > Out of curiousity, how does dspam handle multirecipient mail?
                                        >
                                        > > RCPT TO:<foo@...>
                                        > > RCPT TO:<foo2@...>
                                        > < OK
                                        > > DATA
                                        > < OK
                                        > > headers:
                                        > >
                                        > > body
                                        > > .
                                        > < 4xx|5xx
                                        >
                                        > What, if foo2 doesn't want to use dspam? In that case, he would lose the mail
                                        > still. Or am I wrong?

                                        No, DSPAM can be used as an LMTP content-filter, which supports per-user
                                        opt-in or opt-out enrollment. If foo@... is opted-in, then that
                                        message will be quarantined for him and sent to foo2@.... Or it can
                                        be just tagged for foo@... and not for foo2@.... DSPAM is very
                                        flexible in how you use it.

                                        ---
                                        Chris Covington
                                        IT
                                        Plus One Health Management
                                        75 Maiden Lane Suite 801
                                        NY, NY 10038
                                        646-312-6269
                                        http://www.plusoneactive.com
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