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smtp timeout

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  • Richard Smits
    Hello, We have a problem in SMTP communication with some external mailservers. I will explain. If i do a telnet to port 25 on a remote server, I get no
    Message 1 of 6 , Feb 23, 2011
      Hello,

      We have a problem in SMTP communication with some external mailservers.
      I will explain.
      If i do a telnet to port 25 on a remote server, I get no greeting
      message, it just waits. I suppose this is some greeting delay for anti spam.

      But the greeting never comes. But if i press a carriage return, the
      greeting comes after a while.

      Can someone explain this ?

      Show below :
      --------
      telnet mx.ujf.cas.cz 25
      Trying 147.231.100.6...
      Connected to mx.ujf.cas.cz (147.231.100.6).
      Escape character is '^]'.


      554 mx.ujf.cas.cz ESMTP not accepting messages
      500 5.5.1 Command unrecognized: ""
      500 5.5.1 Command unrecognized: ""

      500 5.5.1 Command unrecognized: ""
      --------

      This is after a carriage return... But even the greeting does not show.

      Does anyone has a clue in wich direction i have to look ?

      Our mailservers use postfix, the remote is different each time. The
      message in the logfile is : (another server)
      ------
      (conversation with mailhost.iist.unu.edu[202.175.118.196] timed out
      while receiving the initial server greeting)
      ------

      Greetings .. Richard Smits
    • Ralf Hildebrandt
      ... It comes after 40s! -- Ralf Hildebrandt Geschäftsbereich IT | Abteilung Netzwerk Charité - Universitätsmedizin Berlin Campus Benjamin Franklin
      Message 2 of 6 , Feb 23, 2011
        * Richard Smits <R.Smits@...>:
        > Hello,
        >
        > We have a problem in SMTP communication with some external
        > mailservers. I will explain.
        > If i do a telnet to port 25 on a remote server, I get no greeting
        > message, it just waits. I suppose this is some greeting delay for
        > anti spam.

        It comes after 40s!

        --
        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
        ... So, I tried sending mail there and it worked on the first try: Feb 23 11:54:31 mail postfix/cleanup[23074]: 095F81C362D: warning: header Subject: Test
        Message 3 of 6 , Feb 23, 2011
          * Ralf Hildebrandt <Ralf.Hildebrandt@...>:
          > * Richard Smits <R.Smits@...>:
          > > Hello,
          > >
          > > We have a problem in SMTP communication with some external
          > > mailservers. I will explain.
          > > If i do a telnet to port 25 on a remote server, I get no greeting
          > > message, it just waits. I suppose this is some greeting delay for
          > > anti spam.
          >
          > It comes after 40s!

          So, I tried sending mail there and it worked on the first try:

          Feb 23 11:54:31 mail postfix/cleanup[23074]: 095F81C362D: warning: header Subject: Test postmaster@... from local; from=<...@...> to=<postmaster@...>

          Feb 23 11:55:09 mail postfix/smtp[18516]: setting up TLS connection to mx.ujf.cas.cz[147.231.100.6]:25

          Feb 23 11:55:09 mail postfix/smtp[18516]: certificate verification failed for mx.ujf.cas.cz[147.231.100.6]:25: untrusted issuer
          /C=CZ/ST=Czech Republic/L=Rez/O=UJF AVCR/OU=ITU/CN=UJF AVCR Root CA/emailAddress=info@...

          Feb 23 11:55:09 mail postfix/smtp[18516]: Untrusted TLS connection established to mx.ujf.cas.cz[147.231.100.6]:25: TLSv1 with cipher
          DHE-RSA-AES256-SHA (256/256 bits)

          Feb 23 11:55:09 mail postfix/smtp[18516]: 095F81C362D: to=<postmaster@...>, relay=mx.ujf.cas.cz[147.231.100.6]:25,
          delay=38, delays=0/0/38/0.05, dsn=4.7.1, status=deferred (host mx.ujf.cas.cz[147.231.100.6] said: 451 4.7.1 Greylisting in action,
          please come back later (in reply to RCPT TO command))


          --
          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
        • lst_hoe02@kwsoft.de
          ... It s Sendmail... Maybe some Spam-Attack got them down ;-)
          Message 4 of 6 , Feb 23, 2011
            Zitat von Ralf Hildebrandt <Ralf.Hildebrandt@...>:

            > * Richard Smits <R.Smits@...>:
            >> Hello,
            >>
            >> We have a problem in SMTP communication with some external
            >> mailservers. I will explain.
            >> If i do a telnet to port 25 on a remote server, I get no greeting
            >> message, it just waits. I suppose this is some greeting delay for
            >> anti spam.
            >
            > It comes after 40s!

            It's Sendmail...

            Maybe some Spam-Attack got them down ;-)
          • Richard Smits
            ... Well, from our university computers i do not get a greeting, but from an external server i do get a greeting. I m thinking about a firewall issue here ...
            Message 5 of 6 , Feb 23, 2011
              On 02/23/2011 11:56 AM, lst_hoe02@... wrote:
              > Zitat von Ralf Hildebrandt <Ralf.Hildebrandt@...>:
              >
              >> * Richard Smits <R.Smits@...>:
              >>> Hello,
              >>>
              >>> We have a problem in SMTP communication with some external
              >>> mailservers. I will explain.
              >>> If i do a telnet to port 25 on a remote server, I get no greeting
              >>> message, it just waits. I suppose this is some greeting delay for
              >>> anti spam.
              >>
              >> It comes after 40s!
              >
              > It's Sendmail...
              >
              > Maybe some Spam-Attack got them down ;-)
              >

              Well, from our university computers i do not get a greeting, but from an
              external server i do get a greeting.

              I'm thinking about a firewall issue here ...

              But if anyone has more ideas ...

              Greetings .. Richard
            • lst_hoe02@kwsoft.de
              ... Maybe they are using some RBL or rDNS checking which is slow and even fail for your university IPs. If you have important mail for them you should contact
              Message 6 of 6 , Feb 23, 2011
                Zitat von Richard Smits <R.Smits@...>:

                > On 02/23/2011 11:56 AM, lst_hoe02@... wrote:
                >> Zitat von Ralf Hildebrandt <Ralf.Hildebrandt@...>:
                >>
                >>> * Richard Smits <R.Smits@...>:
                >>>> Hello,
                >>>>
                >>>> We have a problem in SMTP communication with some external
                >>>> mailservers. I will explain.
                >>>> If i do a telnet to port 25 on a remote server, I get no greeting
                >>>> message, it just waits. I suppose this is some greeting delay for
                >>>> anti spam.
                >>>
                >>> It comes after 40s!
                >>
                >> It's Sendmail...
                >>
                >> Maybe some Spam-Attack got them down ;-)
                >>
                >
                > Well, from our university computers i do not get a greeting, but
                > from an external server i do get a greeting.
                >
                > I'm thinking about a firewall issue here ...
                >
                > But if anyone has more ideas ...

                Maybe they are using some RBL or rDNS checking which is slow and even
                fail for your university IPs. If you have important mail for them you
                should contact the remote postmaster for whitelisting you.

                Regards

                Andreas
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