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Hi, I've waded through the Bat Book but haven't come upon anything that will resolve my problem yet. My LAN talks to my ISP's SMTP server (via SMART_HOST). If I ...
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  1. #1
    scm
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    Sendmail: subdomain destination problem


    Hi,

    I've waded through the Bat Book but haven't come upon anything that will resolve my problem yet. My LAN talks to my ISP's SMTP server (via SMART_HOST). If I send mail to (eg) user@hosta.com it works fine. If I try to send mail to user@hosta.hostb.com the email is deferred for ever (it retries every 4 hours with the same result - deferred). If I change the address to user%hosta@hostb.com or user%hosta.hostb.com@hostb.com the mail gets sent, but seems to disappear into a black hole (I suspect my ISP's server is doing that) - at least the mail never turns up in the user's mailbox.
    What am I missing? I'm using Fedora Core 2 (soon be upgrading to 3) and sendmail v8.12.11.

    Any hints, please?

    Thanks,
    Steve

  2. #2
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    You haven't really stated enough useful information for problem solving...

    You send to user@hosta.com and it's sent and recieved.
    You send to user@hosta.hostb.com and it's deferred.
    You send to user%hosta@hostb.com and it's sent and not recieved.
    You send to user%hosta.hostb.com@hostb.com and it's sent and not recieved.

    My question is:
    Are you the MX of record for hosta.com and/or hostb.com?
    Blog - KB5UMQ - Linux User #272983
    3 Rules:
    1) "It doesn't work..." is simply not useful information.
    2) Don't cross post!
    3) If you are asking for help, start by telling us your distro/os and version.

  3. #3
    scm
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    Quote Originally Posted by Kode
    You haven't really stated enough useful information for problem solving...

    You send to user@hosta.com and it's sent and recieved.
    You send to user@hosta.hostb.com and it's deferred.
    You send to user%hosta@hostb.com and it's sent and not recieved.
    You send to user%hosta.hostb.com@hostb.com and it's sent and not recieved.

    My question is:
    Are you the MX of record for hosta.com and/or hostb.com?
    Thanks for the response.

    I'm not the MX record for either host and I've disabled MX record checking (MODIFY_MAILER_FLAGS(`SMTP', `+0') in conjunction with nullclient). hosta and hostb are intechangeable in my examples (user@hostb.hosta.com is also deferred). The issue I'm trying to resolve is why an extra domain level causes the email delivery to be deferred.

  4. #4
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    Each subdomain level must have a valid MX record, just like the main domain level. If that MX record doesn't exist, then there's no email handler for it, thus, no route, and thus, deferred.
    Blog - KB5UMQ - Linux User #272983
    3 Rules:
    1) "It doesn't work..." is simply not useful information.
    2) Don't cross post!
    3) If you are asking for help, start by telling us your distro/os and version.

  5. #5
    scm
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    As I've already explained, I've disabled MX checking. The single level domain names I can send to don't have MX records either, and they work. Why don't the subdomain names also work? One of the subdomains does, in fact, have an MX record, but that doesn't work either. So I believe it has nothing to do with MX records. Any other ideas?

    Steve

  6. #6
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    It's not just the MX record itself... the recieving SMTPd needs to know it's supposed to handle that subdomain as well.

    In the sendmail config, for example:

    Code:
    CWhosta.com
    CWhostb.hosta.com
    Etc.
    Blog - KB5UMQ - Linux User #272983
    3 Rules:
    1) "It doesn't work..." is simply not useful information.
    2) Don't cross post!
    3) If you are asking for help, start by telling us your distro/os and version.

  7. #7
    scm
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    The receiving SMTPd can handle the subdomains - it's my sendmail that's deferring the transfer to it! I'm using SMART_HOST to relay all email to my ISP's SMTP server. It only seems to work when there's only one dot in the target's domain address.

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