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Author Topic: E-mail: Why mail servers might block messages  (Read 33701 times)

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Kristoff

    Topic Starter


    Newbie

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    E-mail: Why mail servers might block messages
    « on: January 11, 2022, 02:23:20 AM »
    Hello,

    I have e-mail service provided by two of the largest telecommunications operators in the world: Deutsche Telekom and La Poste S.A. (France).

    There is a strange issue with both systems, where a small proportion of people (maybe 2%?) cannot send me e-mail. So far it has mainly been certain large multinational companies, NGOs, etc.

    I have purchased e-mail service from other large operators such as Protonmail, CompuServe and many others. I have never seen this issue before.

    To anyone with knowledge of SMTP networking: What would cause a Mail Transfer Agent to fail to send to my ISP MTA?

    A spam filter seemed like a simple answer. However, there is no trace of bounced or filtered messages. There is also no pattern as to the blocked organisations or their domain names — and some (multinational corporations) seem far too large to be appearing on spam lists.


    Thank you for your assistance.

    K.

    DaveLembke



      Sage
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    Re: E-mail: Why mail servers might block messages
    « Reply #1 on: January 13, 2022, 03:04:45 PM »
    You might be able to get help from Deutsche Telekom and La Poste S.A. ( France ) to have affected customers have a loopback test performed where they test communications between affected customer and your e-mail to see where its getting lost at. You have no trace of it ever getting to you when checking spam filter and so it seems as though its an issue that is outside of your control to directly troubleshoot locally and you will need help of providers to chase it down.