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Re: avoiding overload on port 587

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  • Tomas Macek
    ... It s because they never had to. It is a historical problem. Now we have thousands of customers, that never had to authenticate, so there is no power to
    Message 1 of 54 , Dec 3, 2012
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      > 2) why would you setup a submission service that doesn't require auth
      > from MUAs?

      It's because they never had to. It is
      a
      historical problem. Now we have thousands of customers, that never had to
      authenticate, so there is no power to force them to do it now.

      These days I'm spending the time by splitting the server into port 25
      (MTA connections) and 587 (MUA connections) - just see my previous
      posts, and can do NOTHING with the
      clients, that never autenticated. I can send them email, to please them,
      and then force
      the authentication on port 587, but I'm pretty sure, that thousands of
      them
      will not reflect the email and they will call here and complain about
      functionality of the email service - this is common for end users
      these days. And after that, I will lose my job... :-) And many of them are
      also unable to reconfigure their Outlooks.

      So the result at submission port must be something like this:

      submission inet n - n - - smtpd
      -o smtpd_etrn_restrictions=reject
      -o smtpd_sasl_auth_enable=yes
      -o content_filter=
      -o receive_override_options=no_header_body_checks
      -o
      smtpd_client_restrictions=check_policy_service,inet:127.0.0.1:24575,permit_mynetworks,permit_sasl_authenticated,reject

      Tomas
    • /dev/rob0
      ... Or better yet: replace it with postscreen. ... To clarify, I meant that if those Outlook Expresses are not yet compromised by malware, they will be, soon.
      Message 54 of 54 , Dec 4, 2012
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        On Tue, Dec 04, 2012 at 07:46:10AM -0600, /dev/rob0 wrote:
        > On Tue, Dec 04, 2012 at 11:59:01PM +1300, Peter wrote:
        > > I would still also set up port 587 on the mail.example.com
        > > IP as submission as well and try to encourage your users (at
        > > least the ones you can) to use port 587 from now on.
        >
        > What I would do, on Linux with IPv4 only, is create the submission
        > port and use an iptables redirect for the alternate IP address:
        >
        > # iptables -vt nat -A PREROUTING -p tcp --dport smtp -d \
        > mail.example.com -j REDIRECT --to-port submission
        >
        > This saves the overhead (system and administrative) of running
        > another smtpd on [mail.example.com]:25; he can leave his "smtp ...
        > smtpd" service alone in master.cf.

        Or better yet: replace it with postscreen.

        > I should also add as a reply to Stan in the other subthread: look
        > above at the first quoted paragraph: "Outlook Expresses setup with
        > ... default configuration."
        >
        > Yikes, bad news, very bad. If not doing content filtering nor
        > policy limitation of submission now, he will be soon. And possibly
        > losing his job in any case. Tomas is not in a good place right now.

        To clarify, I meant that if those Outlook Expresses are not yet
        compromised by malware, they will be, soon.
        --
        http://rob0.nodns4.us/ -- system administration and consulting
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