Skip navigation

Problems to send mail from MS Outlook ...

1829 Views 9 Replies Latest reply: May 9, 2013 7:49 AM by Alfista_SK RSS
Alfista_SK Level 1 Level 1 (0 points)
Currently Being Moderated
May 6, 2013 6:20 AM



I hope that anybody can help me. I have Mountan Lion with latest OS X Server app and from installing I have problems to send mail from MS Outlook. I have Authentication on Automatic and I have removed "reject_non_fqdn_helo_hostname" from file but still can't send the messages. On Mac or iOS is it working.

Please can anybody help me and tell what I need to set that it works?

OS X Server
  • MrHoffman Level 6 Level 6 (11,695 points)
    Currently Being Moderated
    May 6, 2013 7:05 AM (in response to Alfista_SK)

    What are the associated messages in the mail server's SMTP and related logs?

  • MrHoffman Level 6 Level 6 (11,695 points)
    Currently Being Moderated
    May 6, 2013 10:29 AM (in response to Alfista_SK)

    The mail server DNS is incorrect; the forward and reverse translations don't match the MX record for the domain.  That'll cause some mail intended to be sent from remote servers to yours to be dropped on the floor and not sent, and it'll cause mail sent to remote servers also dropped.


    As a test, configure the client for plain text via SSL via the submission port.  (As part of this, don't allow your mail clients to chat with port 25 directly, and make sure SSL/TLS is enabled.)

  • MrHoffman Level 6 Level 6 (11,695 points)
    Currently Being Moderated
    May 9, 2013 5:26 AM (in response to Alfista_SK)

    OS X Server 10.6 didn't care about local DNS quite as much as do later releases of OS X.


    DNS is a fundamental part of network security, and of SSL/TLS network encryption.


    Beyond some basics, your local mail server doesn't really care about DNS, either.  It is the other mail servers on the network that care about your DNS, as you do not want your mail server to be indistinguishable from a spam engine.  Other mail servers will evaluate your DNS, and will determine you're a spam engine, and will not bother sending you mail, or will simply drop mail your server has sent out.


    993 and 995 are IMAP SSL/TLS and POP SSL/TLS ports; these ports are used to read mail.


    Mail servers use TCP 25 to communicate server-to-server, and sometimes client-to-server.


    What's variously considered good networking practice has outbound TCP port 25 traffic blocked, as that suppresses the ability of spam engines and unauthorized SMTP servers from sending out messages.  This is one of the reasons why having clients communicate with servers via port 25 isn't reliable.  There are other reasons.


    The SMTP submission ports are TCP 587 and the legacy submission port is TCP 465.


    Apple has published a list of IP ports used by iOS and OS X applications (TS1629).


    If you're getting an encryption error rather than a credentials error, then there's either a low-level error with your SSL/TLS implementation, or a very fundamental incompatibility. 


    If you're getting credentials or authentication errors and not encryption errors, then you will want to look at the documentation for the particular version of the mail client(s) your folks are using and also at your mail server logs to determine what password mechanism is being used (and rejected) by the particular clients, and then use Server or to configure the authentication available on the mail server.


    As mentioned in an earlier reply, ensure your server is configured to permit SSL/TLS on the submission ports and also SSL/TLS on POP and/or IMAP ports, then try enabling plain-text authentication.  I generally don't allow any non-SSL/TLS connections, and typical practices with mail servers now often deprecate unencrypted client-server connections.


    The exact text of the diagnostics you're getting here can be important, too.  What sort of encryption or credentials diagnostic is being displayed here.

  • MrHoffman Level 6 Level 6 (11,695 points)
    Currently Being Moderated
    May 9, 2013 7:37 AM (in response to Alfista_SK)

    Confusingly, Microsoft Outlook and Microsoft Outlook Express are different products, and there are different versions of each.  Can you post details of which client and version you have here?


    I do not have recent experience with Microsoft Outlook or Outlook Express products, and do not have any Microsoft Outlook or Outlook Express clients connected to the local OS X Server to test with, so I'm not going to be able to provide assistance there. 


    Consider asking some Microsoft folks how to get that client to communicate with a generic Unix or Linux mail server that's running Postfix & Dovecot; these are common mail servers on the 'net, and somebody that knows Microsoft Outlook may (will?) know some details of connecting to these mail servers.


    As for the "encryption" error, please do not paraphrase the wording of the error message(s) or diagnostics you're seeing.  The exact text of the diagnostic often matters a great deal for these sorts of questions.


    Microsoft Outlook is a mail client primarily intended for use with Microsoft Exchange Server, and not a mail client that's more typically used with other mail servers.  AFAIK, it can work, but at least the older versions of Microsoft Outlook had all sorts of issues with non-Microsoft mail servers.


    Microsoft Outlook Express is a Microsoft mail client that is more commonly used with mixed-network and non-Microsoft configurations; with Unix and Linux (and OS X Server) mail servers.  Here is a write-up on getting Outlook Express working with PostfixHere are Microsoft's general Outlook Express instructionsHere are some related instructions for both Outlook and Outlook Express.


    Again, I have no Microsoft Outlook or Microsoft Outlook Express clients available to test with, and would suggest trying a Microsoft forum for this question — while they probably won't know from OS X Server here, they likely do have experience with connecting to Postfix and Dovecot servers, which are the packages used on OS X Server.


More Like This

  • Retrieving data ...

Bookmarked By (0)


  • This solved my question - 10 points
  • This helped me - 5 points
This site contains user submitted content, comments and opinions and is for informational purposes only. Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site. All postings and use of the content on this site are subject to the Apple Support Communities Terms of Use.