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  1. #1
    Join Date
    Jan 2005
    Location
    Newfoundland, Canada
    Posts
    253

    Trouble with Exim and my Current Host

    I have clients that I host that can't email certain domains which I know do exist.

    The support people are telling me that the domain name doesn't resolve, yet the MX records and everything are correct for the particular domain that these people are either sending email to or receiving email from.

    For example:

    If a user I host sends and email to user@domainx.com ... they receive one of two messages:

    retry timeout exceeded

    or

    retry time not reached for any host after a long failure period


    If user@domainx.com sends and email to anyone that host, they receive a bounce back with a message saying that mail delivery was delayed for xx hours and will try for up to 5 days. It will eventually fail.

    domainx.com is perhaps one of the largest ISPs in Canada and my host is telling me that everything is working OK because they can send / receive mail from gmail to my customers.

    Anyone have any suggestions on what to look for?

    I don't think my host is capable of solving this!

  2. #2
    Join Date
    Feb 2006
    Location
    Pakistan/India/USA
    Posts
    322

    Re:

    Dear geekie246,

    Did you tried to take DNS Report of Domains which are not resolving ?

    Best Regards.
    Tom F - VCA-WM, VCA-Cloud, VCA-DCV, CISSO, CPTE, OSCP, RHCE, RHCT
    Maxim Support - Hosting Solutions & Server Management
    Email : tom@maximsupport.com
    Web : http://www.maximsupport.com

  3. #3
    Join Date
    Jan 2005
    Location
    Newfoundland, Canada
    Posts
    253
    Yes, I ran the email test and it finds the correct MX record at the smtp server ...

    Plus, have tried other systems and they all resolve the correct MX record for the domain in question.

    I can send to the user@domainx.com from any other email account, or any other ISP, except for those associated with my reseller account, mail gets successfully delivered to user@domainx.com.

    I'm getting complaints from all the domains that I host about this issue, and I'm stuck ... zero technical support is doing .... they keep telling me it's not a valid domain that my customers are sending to, yet it's one of the LARGEST ISPs in our country here and several of the emails I've been sending to for about 9 years so I know they are valid.

  4. #4
    Join Date
    Jan 2007
    Posts
    31
    How about sending email between the clients that you host (internal test email)? Is there any issue with it? Are you using firewall? Have you tried to temporary disable your firewall and try to send email to user@domainx.com from one of your reseller account?
    eSupportPro.com
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  5. #5
    Good ol' EXIM.

    Your host may be using the "callout" spam checking "feature"

    What it does is this:

    on receiving an inbound connection, it tries to open up a outbound connection to the other server and start to send an email to the null user to see if the other server accepts bounces.

    What goes wrong is this:

    the original server might not accept mail to the null user, or,
    the original server might also want to do the same test, or
    the original server might refuse the connection because the dns records of the exim server are hosed.

    The result, is a mexican standoff.

    I have seen this personally, and I did not bother telling the idiot about it because they could not accept email from me anyways.

    It is the most ill-advised spam control *feature* I have ever seen.

    Wave the next time you go past Holyrood
    Last edited by plumsauce; 08-28-2007 at 02:42 AM.
    edgedirector.com
    managed dns global failover and load balance (gslb)
    exactstate.com
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  6. #6
    Join Date
    Jan 2005
    Location
    Newfoundland, Canada
    Posts
    253
    Quote Originally Posted by Jacklyn View Post
    How about sending email between the clients that you host (internal test email)? Is there any issue with it? Are you using firewall? Have you tried to temporary disable your firewall and try to send email to user@domainx.com from one of your reseller account?

    All mails are delivered internally from all the domains that I host. No issues.

    The host that I'm using is firewalled and they have indicated that they had removed the firewall completely at one point. Same result.

    Thanks for the suggestions though ... I had thought of those things early in the process!

  7. #7
    Join Date
    Jan 2005
    Location
    Newfoundland, Canada
    Posts
    253
    Quote Originally Posted by plumsauce View Post
    Good ol' EXIM.

    Your host may be using the "callout" spam checking "feature"

    What it does is this:

    on receiving an inbound connection, it tries to open up a outbound connection to the other server and start to send an email to the null user to see if the other server accepts bounces.

    What goes wrong is this:

    the original server might not accept mail to the null user, or,
    the original server might also want to do the same test, or
    the original server might refuse the connection because the dns records of the exim server are hosed.

    The result, is a mexican standoff.

    I have seen this personally, and I did not bother telling the idiot about it because they could not accept email from me anyways.

    It is the most ill-advised spam control *feature* I have ever seen.

    Wave the next time you go past Holyrood
    And how would one go about checking if this is the case?

  8. #8
    Join Date
    Apr 2003
    Location
    Melbourne, AU
    Posts
    539
    Quote Originally Posted by plumsauce View Post
    Good ol' EXIM. Your host may be using the "callout" spam checking "feature" What it does is this:

    ...

    It is the most ill-advised spam control *feature* I have ever seen.
    You have a misconstrued view of sender callout. One third is roughly right, another third is inaccurate, while the rest does not happen with a sane Exim config. I can address these if you open a topic on it.
    WK Woon
    CTO | http://www.aflexi.net - A flexible Network
    Building the next generation CDN platform - DEMO .... coming soon

  9. #9
    Join Date
    Apr 2003
    Location
    Melbourne, AU
    Posts
    539
    geekie246, if you have local access to the system, try running this php script to determine how the mail will be routed on your host's server:

    <?php passthru('/usr/sbin/exim -bt recipient@domain.com'); ?>

    (presuming exim's in /usr/sbin.. adjust to suit)
    WK Woon
    CTO | http://www.aflexi.net - A flexible Network
    Building the next generation CDN platform - DEMO .... coming soon

  10. #10
    Join Date
    Jan 2005
    Location
    Newfoundland, Canada
    Posts
    253
    I run this script and it goes out and apparently finds the smtp servers ...

    Looks like it is a valid response. I would post the results here but do not want to have this person subjected to a pile of spam. LOL! Then again, they aren't receiving any email so that won't be a problem.

    LOL!

  11. #11
    Join Date
    Apr 2003
    Location
    Melbourne, AU
    Posts
    539
    So it isn't a DNS problem eh.
    WK Woon
    CTO | http://www.aflexi.net - A flexible Network
    Building the next generation CDN platform - DEMO .... coming soon

  12. #12
    Join Date
    Jan 2005
    Location
    Newfoundland, Canada
    Posts
    253
    Nope.

    It is working now however. But I'm not sure for how long and I am not sure what the host has done to make it work.

  13. #13
    Join Date
    Mar 2003
    Location
    Canada
    Posts
    9,072
    Quote Originally Posted by geekie246 View Post
    Nope.

    It is working now however. But I'm not sure for how long and I am not sure what the host has done to make it work.
    What ISP is this?

    Rogers, Aliant (Bell), Shaw or Telus?
    RACK911 Labs | Penetration Testing | https://www.RACK911Labs.ca

    www.HostingSecList.com - Security Notices for the Hosting Community.

  14. #14
    Join Date
    Jan 2005
    Location
    Newfoundland, Canada
    Posts
    253
    Aliant (Bell)

    Any mail from anyting related to their network was being hosed!

    Working again now though

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