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    And as you were sending via IPv6, and utoronto.ca's SPF record does
    not contain *any* IPv6 statements at all, then Google will block all
    IPv6 mail traffic from utoronto.ca (regardless of whether it comes
    from your ZendTo server or your university's central outgoing mail
    servers).<br>
    <br>
    If utoronto.ca has any IPv6 network in place (which they appear to,
    as you could get to Google via IPv6), then they really should add an
    IPv6 statement to their SPF record. Or else no-one is going to want
    to receive any IPv6 mail they send.<br>
    <br>
    Cheers,<br>
    Jules.<br>
    <br>
    <br>
    <div class="moz-cite-prefix">On 13/01/2017 16:14, Mike Brudenell
      wrote:<br>
    </div>
    <blockquote
cite="mid:CAPXCWavXdHGsbsa9+oKXmWcyLdVe5FZddqi4gANru-jWqkhkLA@mail.gmail.com"
      type="cite">
      <div dir="ltr">As Jules says, this error implies that your server
        is trying to send the message direct to Google. But there are
        (at least) two issues with this:
        <div>
          <ol>
            <li>It looks to be that your server can talk IPv6 and is
              doing so direct to Google's mail servers, but that these
              are detecting a problem with your DNS records as they
              describe in the error response.<br>
              <br>
            </li>
            <li>If you're sending from an "@<a moz-do-not-send="true"
                href="http://utoronto.ca">utoronto.ca</a>" email address
              then there is an SPF record published in the DNS for the <a
                moz-do-not-send="true" href="http://utoronto.ca">utoronto.ca</a>
              domain saying that servers with IP addresses in the
              netblocks ip4:<a moz-do-not-send="true"
                href="http://128.100.132.0/24"><font color="red"><b>MailScanner
                    has detected a possible fraud attempt from
                    "128.100.132.0" claiming to be</b></font>
                128.100.132.0/24</a> and ip4:<a moz-do-not-send="true"
                href="http://128.100.46.0/24"><font color="red"><b>MailScanner
                    has detected a possible fraud attempt from
                    "128.100.46.0" claiming to be</b></font>
                128.100.46.0/24</a> should be sending out messages from
              "@<a moz-do-not-send="true" href="http://utoronto.ca">utoronto.ca</a>"
              addresses and others shouldn't really be.</li>
          </ol>
          <div>As Jules says, the best thing is to get the emails sent
            from your server to be relayed out through your
            organisation's central mail gateways/smarthosts.</div>
        </div>
        <div><br>
        </div>
        <div>Cheers,</div>
        <div>Mike B-)</div>
        <div><br>
        </div>
        <div>PS. Have just read your latest message: glad you've spotted
          the issue.</div>
      </div>
      <div class="gmail_extra"><br>
        <div class="gmail_quote">On 13 January 2017 at 15:37, Brian
          Novogradac <span dir="ltr">&lt;<a moz-do-not-send="true"
              href="mailto:Brian.Novogradac@utoronto.ca" target="_blank">Brian.Novogradac@utoronto.ca</a>&gt;</span>
          wrote:<br>
          <blockquote class="gmail_quote" style="margin:0 0 0
            .8ex;border-left:1px #ccc solid;padding-left:1ex">
            <div link="blue" vlink="purple" lang="EN-US">
              <div class="m_8667406008319791906WordSection1">
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Here
                    is the error from my root mailbox
                  </span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d"> </span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d"> </span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">  
                    ----- The following addresses had permanent fatal
                    errors -----</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">&lt;<a
                      moz-do-not-send="true"
                      href="mailto:user@gmail.com" target="_blank">user@gmail.com</a>&gt;</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">   
                    (reason: 550-5.7.1 [2606:fa00:400:2006:250:56ff:<wbr>fe92:282a]
                    Our system has detected that)</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d"> </span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">  
                    ----- Transcript of session follows -----</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">...
                    while talking to <a moz-do-not-send="true"
                      href="http://gmail-smtp-in.l.google.com"
                      target="_blank">gmail-smtp-in.l.google.com</a>.:</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">&gt;&gt;&gt;
                    DATA</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">&lt;&lt;&lt;
                    550-5.7.1 [2606:fa00:400:2006:250:56ff:<wbr>fe92:282a]
                    Our system has detected that</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">&lt;&lt;&lt;
                    550-5.7.1 this message does not meet IPv6 sending
                    guidelines regarding PTR</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">&lt;&lt;&lt;
                    550-5.7.1 records and authentication. Please review</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">&lt;&lt;&lt;
                    550-5.7.1  <a moz-do-not-send="true"
                      href="https://support.google.com/mail/?p=IPv6AuthError"
                      target="_blank">https://support.google.com/<wbr>mail/?p=IPv6AuthError</a>
                    for more information</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">&lt;&lt;&lt;
                    550 5.7.1 . u130si1909083iod.170 - gsmtp</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">554
                    5.0.0 Service unavailable</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d"> </span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">--v0DDJKOE005944.1484313560/<a
                      moz-do-not-send="true"
                      href="http://send.utoronto.ca" target="_blank">se<wbr>nd.utoronto.ca</a></span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Content-Type:
                    message/delivery-status</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d"> </span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Reporting-MTA:
                    dns; <a moz-do-not-send="true"
                      href="http://send.utoronto.ca" target="_blank">send.utoronto.ca</a></span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Received-From-MTA:
                    DNS; localhost.localdomain</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Arrival-Date:
                    Fri, 13 Jan 2017 08:19:19 -0500</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d"> </span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Final-Recipient:
                    RFC822; <a moz-do-not-send="true"
                      href="mailto:user@gmail.com" target="_blank">user@gmail.com</a></span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Action:
                    failed</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Status:
                    5.7.1</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Remote-MTA:
                    DNS; <a moz-do-not-send="true"
                      href="http://gmail-smtp-in.l.google.com"
                      target="_blank">gmail-smtp-in.l.google.com</a></span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Diagnostic-Code:
                    SMTP; 550-5.7.1 [2606:fa00:400:2006:250:56ff:<wbr>fe92:282a]
                    Our system has detected that</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Last-Attempt-Date:
                    Fri, 13 Jan 2017 08:19:20 -0500</span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d"> </span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">--v0DDJKOE005944.1484313560/<a
                      moz-do-not-send="true" href="http://zendto.XXX.ca"
                      target="_blank">ze<wbr>ndto.XXX.ca</a></span></p>
                <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d"> </span></p>
                <p class="MsoNormal"><b><span
                      style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">From:</span></b><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif"> <a
                      moz-do-not-send="true"
                      href="mailto:zendto-bounces@zend.to"
                      target="_blank">zendto-bounces@zend.to</a>
                    [mailto:<a moz-do-not-send="true"
                      href="mailto:zendto-bounces@zend.to"
                      target="_blank">zendto-bounces@zend.to</a><wbr>]
                    <b>On Behalf Of </b>Mike Brudenell<br>
                    <b>Sent:</b> Friday, January 13, 2017 9:40 AM<span
                      class=""><br>
                      <b>To:</b> ZendTo Users &lt;<a
                        moz-do-not-send="true"
                        href="mailto:zendto@zend.to" target="_blank">zendto@zend.to</a>&gt;<br>
                      <b>Subject:</b> Re: [ZendTo] Issues with sending
                      to external users</span></span></p>
                <p class="MsoNormal"> </p>
                <div>
                  <div>
                    <p class="MsoNormal">Hi, Brian -</p>
                  </div>
                  <div>
                    <div class="h5">
                      <div>
                        <p class="MsoNormal"> </p>
                      </div>
                      <div>
                        <p class="MsoNormal">Firstly note that I've not
                          touched Sendmail since 2008 (we use Exim now)
                          so my memory/interpretation might be hazy in
                          places in my comments below…</p>
                      </div>
                      <div>
                        <p class="MsoNormal"> </p>
                      </div>
                      <div>
                        <div>
                          <p class="MsoNormal">On 13 January 2017 at
                            13:31, Brian Novogradac &lt;<a
                              moz-do-not-send="true"
                              href="mailto:Brian.Novogradac@utoronto.ca"
                              target="_blank">Brian.Novogradac@utoronto.ca</a>&gt;
                            wrote:</p>
                          <blockquote
                            style="border:none;border-left:solid #cccccc
                            1.0pt;padding:0in 0in 0in
                            6.0pt;margin-left:4.8pt;margin-right:0in">
                            <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Thanks
                                for helping me out here here is some
                                more information.</span></p>
                            <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d"> </span></p>
                            <p
                              class="m_8667406008319791906gmail-m-4670916704799623933msolistparagraph"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">-</span><span
                                style="font-size:7.0pt;color:#1f497d">         
                              </span><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Running
                                Centos 6.8</span></p>
                            <p
                              class="m_8667406008319791906gmail-m-4670916704799623933msolistparagraph"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">-</span><span
                                style="font-size:7.0pt;color:#1f497d">         
                              </span><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Yes
                                the zendto is sending messages to
                                sendmail on the machine</span></p>
                            <p
                              class="m_8667406008319791906gmail-m-4670916704799623933msolistparagraph"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">-</span><span
                                style="font-size:7.0pt;color:#1f497d">         
                              </span><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">I
                                have all hostname information set
                                correctly in hosts file</span></p>
                            <p
                              class="m_8667406008319791906gmail-m-4670916704799623933msolistparagraph"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">-</span><span
                                style="font-size:7.0pt;color:#1f497d">         
                              </span><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">In
                                <a moz-do-not-send="true"
                                  href="http://sendmail.mc"
                                  target="_blank">sendmail.mc</a> I have
                                added the domainname in
                                define(`confDOMAIN_NAME', `<a
                                  moz-do-not-send="true"
                                  href="http://zendto.host.ca"
                                  target="_blank">zendto.host.ca</a>')dnl</span></p>
                          </blockquote>
                          <div>
                            <p class="MsoNormal">I seem to remember that
                              you set confDOMAIN_NAME to the domain name
                              you want adding to unqualified addresses —
                              ie, those that are only a username. If you
                              have
                              <u>really</u> set this to "<a
                                moz-do-not-send="true"
                                href="http://zendto.host.ca"
                                target="_blank">zendto.host.ca</a>" then
                              a message from/to the plain username
                              address</p>
                          </div>
                          <div>
                            <p class="MsoNormal"> </p>
                          </div>
                        </div>
                      </div>
                      <blockquote
                        style="margin-left:30.0pt;margin-right:0in">
                        <div>
                          <div>
                            <div>
                              <p class="MsoNormal">apache</p>
                            </div>
                          </div>
                        </div>
                      </blockquote>
                      <div>
                        <p class="MsoNormal"> </p>
                      </div>
                      <p class="MsoNormal">say, becomes</p>
                      <div>
                        <p class="MsoNormal"> </p>
                      </div>
                      <div>
                        <blockquote
                          style="margin-left:30.0pt;margin-right:0in">
                          <div>
                            <p class="MsoNormal"><a
                                moz-do-not-send="true"
                                href="mailto:apache@zendto.host.ca"
                                target="_blank">apache@zendto.host.ca</a></p>
                          </div>
                        </blockquote>
                        <div>
                          <p class="MsoNormal"> </p>
                        </div>
                        <p class="MsoNormal">I've used dig to look up
                          data for the domain "<a moz-do-not-send="true"
                            href="http://host.ca" target="_blank">host.ca</a>"
                          and to be honest I'm not convinced you've
                          really set it to that as it seems to be
                          something to do with <a moz-do-not-send="true"
                            href="http://domainsatcost.ca"
                            target="_blank">domainsatcost.ca</a>.</p>
                        <div>
                          <div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <blockquote
                              style="border:none;border-left:solid
                              #cccccc 1.0pt;padding:0in 0in 0in
                              6.0pt;margin-left:4.8pt;margin-right:0in">
                              <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Maillog:</span></p>
                              <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d"> </span></p>
                              <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Jan
                                  13 08:19:19 zendto sendmail[5941]:
                                  v0DDJILc005941: from=apache,
                                  size=1517, class=0, nrcpts=1,
                                  msgid=&lt;<a moz-do-not-send="true"
                                    href="mailto:201701131319.v0DDJILc005941@zendto.XXXXX"
                                    target="_blank">201701131319.<wbr>v0DDJILc005941@zendto.XXXXX</a>&gt;,
                                  relay=apache@localhost</span></p>
                            </blockquote>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal">The above will be the
                                locally generated message your apache
                                username is creating and handing to
                                Sendmail.</p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <blockquote
                              style="border:none;border-left:solid
                              #cccccc 1.0pt;padding:0in 0in 0in
                              6.0pt;margin-left:4.8pt;margin-right:0in">
                              <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Jan
                                  13 08:19:19 zendto sendmail[5942]:
                                  v0DDJJOE005942: from=<a class="moz-txt-link-rfc2396E" href="mailto:apache@zendto.XXXXX">&lt;apache@
                                  zendto.XXXXX &gt;</a>, size=1744, class=0,
                                  nrcpts=1, msgid=&lt;201701131319.<wbr>v0DDJILc005941@
                                  zendto.XXXXX &gt;, proto=ESMTP,
                                  daemon=MTA,
                                  relay=localhost.localdomain
                                  [127.0.0.1]</span></p>
                            </blockquote>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal">Then sendmail
                                qualifies the plain sender address
                                "apache" with a domain name, making it
                                &lt;apache.zendto.XXXXX&gt; — hmm, if
                                that's the case then that won't be a
                                valid email address.</p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal">I seem to recall that
                                "relay=" identifies the server the
                                message is transmitted onward to: in
                                this case to the SMTP server running on
                                the same machine — localhost.localdomain
                                [127.0.0.1]</p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <blockquote
                              style="border:none;border-left:solid
                              #cccccc 1.0pt;padding:0in 0in 0in
                              6.0pt;margin-left:4.8pt;margin-right:0in">
                              <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Jan
                                  13 08:19:19 zendto sendmail[5941]:
                                  v0DDJILc005941: to=<a
                                    moz-do-not-send="true"
                                    href="mailto:userXXX@gmail.com"
                                    target="_blank">userXXX@gmail.com</a>,
                                  ctladdr=apache (48/48),
                                  delay=00:00:01, xdelay=00:00:00,
                                  mailer=relay, pri=31517,
                                  relay=[127.0.0.1] [127.0.0.1],
                                  dsn=2.0.0, stat=Sent (v0DDJJOE005942
                                  Message accepted for delivery)</span></p>
                            </blockquote>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal">I think the above is
                                Sendmail logging it has successfully
                                transmitted your message to the SMTP
                                listener running on your host.</p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <blockquote
                              style="border:none;border-left:solid
                              #cccccc 1.0pt;padding:0in 0in 0in
                              6.0pt;margin-left:4.8pt;margin-right:0in">
                              <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Jan
                                  13 08:19:20 zendto sendmail[5944]:
                                  STARTTLS=client, relay=<a
                                    moz-do-not-send="true"
                                    href="http://gmail-smtp-in.l.google.com"
                                    target="_blank">gmail-smtp-in.l.google.<wbr>com</a>.,
                                  version=TLSv1/SSLv3, verify=FAIL,
                                  cipher=ECDHE-RSA-AES128-GCM-<wbr>SHA256,
                                  bits=128/128</span></p>
                            </blockquote>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal">Your Sendmail then
                                decides it needs to transmit the message
                                to the server <a moz-do-not-send="true"
href="http://gmail-smtp-in.l.google.com" target="_blank">gmail-smtp-in.l.google.<wbr>com</a></p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal">Which tallies with
                                the MX records for <a
                                  moz-do-not-send="true"
                                  href="http://gmail.com"
                                  target="_blank">
                                  gmail.com</a> — these have the most
                                preferred one being <a
                                  moz-do-not-send="true"
                                  href="http://gmail-smtp-in.l.google.com"
                                  target="_blank">gmail-smtp-in.l.google.<wbr>com</a></p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <blockquote
                              style="border:none;border-left:solid
                              #cccccc 1.0pt;padding:0in 0in 0in
                              6.0pt;margin-left:4.8pt;margin-right:0in">
                              <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Jan
                                  13 08:19:20 zendto sendmail[5944]:
                                  v0DDJJOE005942: to=&lt;
                                  <a moz-do-not-send="true"
                                    href="mailto:userXXX@gmail.com"
                                    target="_blank">userXXX@gmail.com</a>
                                  &gt;, ctladdr=&lt;apache@ zendto.XXXXX
                                  &gt; (48/48), delay=00:00:01,
                                  xdelay=00:00:01, mailer=esmtp,
                                  pri=121744, relay=<a
                                    moz-do-not-send="true"
                                    href="http://gmail-smtp-in.l.google.com"
                                    target="_blank">gmail-smtp-in.l.google.<wbr>com</a>.
                                  [IPv6:2607:f8b0:4001:c01::1b],
                                  dsn=5.0.0, stat=Service unavailable</span></p>
                            </blockquote>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal">The above line is
                                Gmail's SMTP server refusing to accept
                                your message, returning a 5xx permanent
                                failure response code, with the rather
                                unhelpful explanatory text "Service
                                unavailable".</p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal">The 5xx response code
                                tells your Sendmail to abandon any
                                further attempts to send the message and
                                to generate a Non-Delivery Report to
                                return to the sender.</p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <blockquote
                              style="border:none;border-left:solid
                              #cccccc 1.0pt;padding:0in 0in 0in
                              6.0pt;margin-left:4.8pt;margin-right:0in">
                              <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Jan
                                  13 08:19:20 zendto sendmail[5944]:
                                  v0DDJJOE005942: v0DDJKOE005944: DSN:
                                  Service unavailable</span></p>
                              <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Jan
                                  13 08:19:20 zendto sendmail[5944]:
                                  v0DDJKOE005944: to=root,
                                  delay=00:00:00, xdelay=00:00:00,
                                  mailer=local, pri=32992, dsn=2.0.0,
                                  stat=Sent</span></p>
                            </blockquote>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal">This shows a message
                                being delivered to the local mailbox
                                belonging to the root username on your
                                server — ie, the Zendto box. Check in
                                that mailbox and you'll likely find the
                                Non-Delivery Report, hopefully with some
                                information about why the message was
                                rejected by Gmail.</p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal">Things that trouble
                                me are the stray spaces everywhere. For
                                example the sender address seems to
                                be &lt;apache@ zendto.XXXXX &gt; and the
                                recipient address &lt;
                                <a moz-do-not-send="true"
                                  href="mailto:userXXX@gmail.com"
                                  target="_blank">userXXX@gmail.com</a>
                                &gt;. But a quick test suggests Gmail
                                would reject these with a "555 5.5.2
                                Syntax error." response rather than
                                "Service unavailable".</p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <div>
                              <p class="MsoNormal"> </p>
                            </div>
                            <blockquote
                              style="border:none;border-left:solid
                              #cccccc 1.0pt;padding:0in 0in 0in
                              6.0pt;margin-left:4.8pt;margin-right:0in">
                              <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">Email
                                  Header:</span></p>
                              <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d"> </span></p>
                              <p class="MsoNormal">Received: from
                                zendto.XXXXX (localhost.localdomain
                                [127.0.0.1]) by<br>
                                zendto.XXXXX t(8.14.4/8.14.4) with ESMTP
                                id v0CJ8WAd001980; Thu, 12 Jan<br>
                                2017 14:08:32 -0500<br>
                                Received: (from <a
                                  moz-do-not-send="true"
                                  href="mailto:apache@localhost"
                                  target="_blank">apache@localhost</a>)
                                by
                                <span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1f497d">zendto.XXXXX
                                </span>(8.14.4/8.14.4/Submit)<br>
                                id v0CJ8Wm9001976; Thu, 12 Jan 2017
                                14:08:32 -0500<br>
                                Date: Thu, 12 Jan 2017 14:08:32 -0500<br>
                                Message-ID: &lt;<a
                                  moz-do-not-send="true"
                                  href="mailto:201701121908.v0CJ8Wm9001976@send.utoronto.ca"
                                  target="_blank">201701121908.v0CJ8Wm9001976@<span
style="color:windowtext;text-decoration:none">
                                  </span>zendto.XXXXX </a>&gt;<br>
                                To: &lt; <span style="color:#1f497d"><a
                                    moz-do-not-send="true"
                                    href="mailto:userXXX@gmail.com"
                                    target="_blank">userXXX@gmail.com</a>
                                </span>&gt;<br>
                                Subject: User has dropped off a file for
                                you<br>
                                X-PHP-Originating-Script:
                                0:NSSDropbox.php<br>
                                From: Zendto &lt;<a
                                  moz-do-not-send="true"
                                  href="mailto:no-reply@utoronto.ca"
                                  target="_blank">no-reply@<span
                                    style="color:windowtext;text-decoration:none">
                                  </span>zendto.XXXXX </a>&gt;</p>
                            </blockquote>
                          </div>
                          <p class="MsoNormal"><br>
                            Basically there's still a lot of
                            obfuscation, possibly along with some typos
                            (the stray spaces) introduced whilst
                            obfuscating, for anyone else to be sure
                            what's going on. You'll need to discuss your
                            pristine logs with a local Sendmail support
                            guru at your site.<br>
                            <br>
                            Cheers,</p>
                        </div>
                        <div>
                          <p class="MsoNormal">Mike B.<br clear="all">
                          </p>
                          <div>
                            <p class="MsoNormal"> </p>
                          </div>
                          <p class="MsoNormal">-- </p>
                          <div>
                            <div>
                              <div>
                                <p class="MsoNormal"><span
                                    style="color:#666666">Systems
                                    Administrator &amp; Change Manager</span></p>
                              </div>
                              <div>
                                <p class="MsoNormal"><span
                                    style="color:#666666">IT Services,
                                    University of York, Heslington, York
                                    YO10 5DD, UK</span></p>
                              </div>
                              <div>
                                <p class="MsoNormal"><span
                                    style="color:#666666">Tel: <a
                                      moz-do-not-send="true"
                                      href="tel:01904%20323811"
                                      value="+441904323811"
                                      target="_blank">+44-(0)1904-323811</a></span></p>
                              </div>
                              <div>
                                <p class="MsoNormal"> </p>
                              </div>
                              <div>
                                <p class="MsoNormal"><span
                                    style="color:#666666">Web:               
                                    <a moz-do-not-send="true"
                                      href="http://www.york.ac.uk/it-services"
                                      target="_blank">
                                      www.york.ac.uk/it-services</a></span></p>
                              </div>
                              <div>
                                <p class="MsoNormal"><span
                                    style="color:#666666">Disclaimer:     
                                    <a moz-do-not-send="true"
                                      href="http://www.york.ac.uk/docs/disclaimer/email.htm"
                                      target="_blank">
                                      www.york.ac.uk/docs/<wbr>disclaimer/email.htm</a></span></p>
                              </div>
                            </div>
                          </div>
                        </div>
                      </div>
                    </div>
                  </div>
                </div>
              </div>
            </div>
            <br>
            ______________________________<wbr>_________________<br>
            ZendTo mailing list<br>
            <a moz-do-not-send="true" href="mailto:ZendTo@zend.to">ZendTo@zend.to</a><br>
            <a moz-do-not-send="true"
              href="http://mailman.ecs.soton.ac.uk/mailman/listinfo/zendto"
              rel="noreferrer" target="_blank">http://mailman.ecs.soton.ac.<wbr>uk/mailman/listinfo/zendto</a><br>
          </blockquote>
        </div>
        <br>
        <br clear="all">
        <div><br>
        </div>
        -- <br>
        <div class="gmail_signature" data-smartmail="gmail_signature">
          <div dir="ltr">
            <div><font color="#666666">Systems Administrator &amp;
                Change Manager</font></div>
            <div><font color="#666666">IT Services, University of York,
                Heslington, York YO10 5DD, UK</font></div>
            <div><font color="#666666">Tel: +44-(0)1904-323811</font></div>
            <div><font color="#666666"><br>
              </font></div>
            <div><font color="#666666">Web:<span style="white-space:pre">                </span><a
                  moz-do-not-send="true"
                  href="http://www.york.ac.uk/it-services"
                  target="_blank">www.york.ac.uk/it-services</a></font></div>
            <div><font color="#666666">Disclaimer:<span style="white-space:pre">        </span><a
                  moz-do-not-send="true"
                  href="http://www.york.ac.uk/docs/disclaimer/email.htm"
                  target="_blank">www.york.ac.uk/docs/disclaimer/email.htm</a></font></div>
          </div>
        </div>
      </div>
      <br>
      <fieldset class="mimeAttachmentHeader"></fieldset>
      <br>
      <pre wrap="">_______________________________________________
ZendTo mailing list
<a class="moz-txt-link-abbreviated" href="mailto:ZendTo@zend.to">ZendTo@zend.to</a>
<a class="moz-txt-link-freetext" href="http://mailman.ecs.soton.ac.uk/mailman/listinfo/zendto">http://mailman.ecs.soton.ac.uk/mailman/listinfo/zendto</a></pre>
    </blockquote>
    <br>
    <pre class="moz-signature" cols="72">Jules

-- 
Julian Field MEng MBCS CITP CEng

'Learn from yesterday, live for today,
 look to tomorrow, rest this afternoon.' - Charles M Schulz

<a class="moz-txt-link-abbreviated" href="http://www.Zend.To">www.Zend.To</a>
Twitter: @JulesFM
PGP footprint: EE81 D763 3DB0 0BFD E1DC 7222 11F6 5947 1415 B654
</pre>
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