MacSkoog

Q: Mail Server does not always send

I have a vexing problem for our small business Mac OS X server.

 

The server essentially has only 3 users using the mail server.  One user sends 10x more email than the others and is of course the person with this problem.  The problem being that his outgoing emails do not always get sent, or more accurately, not always accepted by the receiving mail server.  The most maddening problem is that he may not get the returned error message for 4 days.  This certainly does not happen with all sent emails, maybe 10%.  Mail is not relayed through the local ISP.

 

Most of the error codes received are complete gibberish to me but the last one said,

 

Diagnostic-Code: smtp; 550 5.7.1 Sorry, message looks like spam or phish to me

   (OP)

 

As best as I can tell, some of the receiving mail servers just do not like the OS X server mail server.  Other emails sent at nearly the same time to non problematic mail addresses work fine.  For instance, he can always send to my iCloud email address.

 

Therefore, I know internet connectivity is good.  The server has a static ip address and is behind an older airport extreme router.  The server does a lot of things, but again serves a very small number of people; mail, file, print, vpn, contacts, profile manager, time machine, caching, calendar, dns.

 

All current updates, etc. have been installed.

 

I would appreciate any diagnostic pointers or help.

Mac Pro, OS X Server, 2.66 quad core xeon 18gb

Posted on Apr 9, 2016 2:55 PM

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Q: Mail Server does not always send

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  • by haykong,

    haykong haykong Apr 9, 2016 8:36 PM in response to MacSkoog
    Level 1 (119 points)
    Apr 9, 2016 8:36 PM in response to MacSkoog

    It seems to me that perhaps your Reverse name lookup might not match which is why some smtp servers that have more restrictions turned and  may think your email is spam which is the error that the other SMTP reported back to you.  Only way to correct this is contact your ISP to correct it.

  • by MacSkoog,

    MacSkoog MacSkoog Apr 10, 2016 6:03 PM in response to haykong
    Level 1 (4 points)
    Servers Enterprise
    Apr 10, 2016 6:03 PM in response to haykong

    Thanks for the response.

     

    Based on your input, I wonder if my setup could be part of the problem or even all of it.  The mail server is located at osxserver.skooghq.com.  The domain that we use for the emails is skooglandscape.com.  I wonder if something is being lost in the translation between the two domains.

     

    Thanks for the help

  • by haykong,

    haykong haykong Apr 10, 2016 11:49 PM in response to MacSkoog
    Level 1 (119 points)
    Apr 10, 2016 11:49 PM in response to MacSkoog

    Ok,  Just checked a few things for you.

     

    As I thought I was right,  there is a SMTP Reverse DNS Mismatch, meaning Reverse DNS does not contain the hostname. Also reverse DNS does not match SMTP Banner. If you do a reverse look up of your IP, your host name is cust-69-197-116-134.wireless.t6b.com.    This is one potential issue  for some of the email problems.

     

    However, I think your other issue is two of the blacklist servers have your IP blacklisted. The IP is blacklisted on Protected Sky and TRUNCATE.

     

    You can verify it on http://mxtoolbox.com/ which is a useful site.

     

    On a side note. Just to tight up security a little when doing an SMTP check on your mail server...

    250-AUTH LOGIN PLAIN CRAM-MD5 DIGEST-MD5 GSSAPI


    It reported that Login and Plain options are available. You might want to turn that off in the custom in authentication in the Mail server portion of OS X Server.

    You also might consider turning on Adaptive Firewall If you haven't done so yet.

    How to enable the adaptive firewall on OS X Server - Apple Support

     

    Hope this helps

  • by pterobyte,

    pterobyte pterobyte Apr 11, 2016 2:01 AM in response to MacSkoog
    Level 6 (11,101 points)
    Servers Enterprise
    Apr 11, 2016 2:01 AM in response to MacSkoog

    Without having more log or configuration information it is difficult to say what your actual problem is. Chances are that, as haykong mentioned, your missing reverse record plays part in it.

     

    That said, your IP has a poor reputation in quite a few databases. Assuming it is a business level service IP, then either it was abused a lot before it was assigned to you, or your server has been compromised at some point and sent out spam. If it is a residential IP, then this is expected behaviour and little you can do about other than ask for another IP wich is not part of some residential or dial-up pool.

     

    HTH,

    Alex

  • by MacSkoog,

    MacSkoog MacSkoog Jul 17, 2016 1:50 PM in response to pterobyte
    Level 1 (4 points)
    Servers Enterprise
    Jul 17, 2016 1:50 PM in response to pterobyte

    My problems continue and are getting worse.  I never have really figured out what the problem was.  I contacted my ISP and had them fix the reverse DNS problem.....I think.

     

    Many of the returned emails are from Gmail, but not all.  The error header is at the bottom.  As I stated before, sending to iCloud addresses do not have a problem.

     

    I have used mxtoolbox.com and I am not sure even what domain is causing the problem...skooglandscape.com or skooghq.com.  Both have errors.  The email server is on skooghq.com and the users are all using skooglandscape.com.  What is Google unhappy about?  The reverse IP6 guideline of reverse lookup?  The means I need a PTR record....where and how?  Why are both domains blacklisted?    They were clear of blacklists back in May.  Have I been hacked by some spammer?

     

    Anyway, I am ready to throw in the towel on my own email server and just go back to using Fatcow's system....but will I run into all of these problems again?  I am out of my league on all of these DNS and MX settings.

     

    My office mates are about to run me out of town on a pole.

    From: MAILER-DAEMON@osxserver.skooghq.com (Mail Delivery System)

    Subject: Undelivered Mail Returned to Sender

    Date: July 16, 2016 at 10:03:51 AM CDT

    To: alan.skoog@skooglandscape.com


    This is the mail system at host osxserver.skooghq.com.

     

    I'm sorry to have to inform you that your message could not
    be delivered to one or more recipients. It's attached below.

     

    For further assistance, please send mail to postmaster.

     

    If you do so, please include this problem report. You can
    delete your own text from the attached returned message.

     

                      The mail system

     

    <ljpayne1234@gmail.com>: host gmail-smtp-in.l.google.com[2607:f8b0:4001:c08::1a]
       said: 550-5.7.1 [2002:45c5:7486:0:4924:7f3f:febe:f132] Our system has
       detected that 550-5.7.1 this message does not meet IPv6 sending guidelines
       regarding PTR 550-5.7.1 records and authentication. Please review 550-5.7.1
       https://support.google.com/mail/?p=ipv6_authentication_error for more 550
       5.7.1 information. j65si808106iod.146 - gsmtp (in reply to end of DATA
       command)
    Reporting-MTA: dns; osxserver.skooghq.com
    X-Postfix-Queue-ID: 98D98147EEF5D
    X-Postfix-Sender: rfc822; alan.skoog@skooglandscape.com
    Arrival-Date: Sat, 16 Jul 2016 10:03:50 -0500 (CDT)

     

    Final-Recipient: rfc822; ljpayne1234@gmail.com
    Original-Recipient: rfc822;ljpayne1234@gmail.com
    Action: failed
    Status: 5.7.1
    Remote-MTA: dns; gmail-smtp-in.l.google.com
    Diagnostic-Code: smtp; 550-5.7.1 [2002:45c5:7486:0:4924:7f3f:febe:f132] Our
       system has detected that 550-5.7.1 this message does not meet IPv6 sending
       guidelines regarding PTR 550-5.7.1 records and authentication. Please
       review 550-5.7.1
       https://support.google.com/mail/?p=ipv6_authentication_error for more 550
       5.7.1 information. j65si808106iod.146 - gsmtp

     

     

    From: Alan Skoog <alan.skoog@skooglandscape.com>

     

    Subject: Powder coating

    Date: July 16, 2016 at 10:03:49 AM CDT

    To: "Mr. Louie Payne" <ljpayne1234@gmail.com>

  • by MacSkoog,

    MacSkoog MacSkoog Jul 17, 2016 2:17 PM in response to MacSkoog
    Level 1 (4 points)
    Servers Enterprise
    Jul 17, 2016 2:17 PM in response to MacSkoog

    As I muck my way further though this I am wondering if the problem is that the reverse lookup of 69.197.116.134 returns...

    mail.skooglandscape.com

     

    and it should instead return....

    mail.skooghq.com

      - or -

    osxserver.skooghq.com

     

    Thanks for any help

     

    Andy