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MailScanner + No A record = no mail delivered

Discussion in 'cPanel Developers' started by bitstream, Jan 12, 2006.

  1. bitstream

    bitstream Member

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    Hello,

    I've noticed a somewhat strange behavior while running Chirpy's MailScanner. If a domain that mail is to be delivered to has no DNS A record associated with it, the mail will not be delivered - you will instead get a bounce message stating that the mail could not be delivered:

    Here is a sample message, unfortunately I have no headers:

    Code:
    The date of the message is: Wed, 04 Jan 2006 16:18:26 -0800
    The subject of the message is: Lab Assistant
    
    The address to which the message has not yet been delivered is:
    
    email address deleted
    
    No action is required on your part. Delivery attempts will continue for
    some time, and this warning may be repeated at intervals if the message
    remains undelivered. Eventually the mail delivery software will give up,
    and when that happens, the message will be returned to you.
    
    The domain in question, edcc.edu, has a proper MX record associated with it, but does not have an A record. When I comment out the following in my exim.conf the mail gets delivered properly, but I believe I am disabling mailscanner by commeting out these directives:

    Code:
            defer_router:
                    driver = redirect
                    allow_defer
                    data = :defer: All deliveries are handled by MailScanner
                    verify = false
    
    Anyone have any suggestions? My user needs to be able to send email to the domain in question, but I need MailScanner running - any ideas?

    Thanks
     
  2. chirpy

    chirpy Well-Known Member

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    For a domain to function correctly it must have an A record otherwise it won't ever resolve correctly. Also, an MX record must point to an A record itself and never to an IP address directly. I'd suggest you contact the owner of the zone and have them fix their DNS. An alternative would be to create an entry in /etc/hosts if that's used first in /etc/host.conf:

    11.22.33.44 domain.com
     
  3. Lyttek

    Lyttek Well-Known Member

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    The MX record for the domain you list is barracuda.edcc.ctc.edu.
    The A record for barracuda.edcc.ctc.edu points to IP 134.39.230.6

    Does MailScanner do some type of filtering that says, based on the different domain names, that a message addressed to someone@edcc.edu but deliverd to barracuda.edcc.ctc.edu is spam? And is this indeed the server on which MailScanner is installed?
     
  4. chirpy

    chirpy Well-Known Member

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    MailScanner doesn't do any such scanning that I'm aware of. I just checked the DNS for edcc.edu and it appears to be fine, though I occassionally got a broken authoratitive DNS server which would definitely cause problems and could explain the intermittent nature of the issue.
     
  5. bitstream

    bitstream Member

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    An A record search for edcc.edu results in no entry.

    An MX record search for edcc.edu results in barracuda.edcc.ctc.edu.

    An A record search for barracuda.edcc.ctc.edu. results in a proper IP.

    So, although it appears it should have everything it needs, mail is still being delayed to that domain. The only thing I can guess is that the lack of a direct A record for edcc.edu is the culprit, but exim on it's own will deliver without any issue. Regardless of whether it should work or not, it's not working now, and I'm stuck.

    Any other ideas?
     
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