Bluewin does not accept emails from your own domain

    • I installed MailPlus on my Synology NAS. To send emails, I use my own domain, which I have parked at a Swiss registrar. Sending and receiving emails works flawlessly… except for bluewin. I can receive emails from bluewin addresses, but bluewin does not accept messages from my domain. Can someone help me and give me a tip as to which settings I should check? I get the following error message:

    host mx-v01.bluewin.ch[195.186.120.50] refused to talk
    to me: 554 mxbw.lb.bluewin.ch vimdzmsp-mxin11.bluewin.ch Swisscom AG IP:
    178.192.101.161, You are not allowed to send us mail. Please see DNSNULL if
    you feel this is in error

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    • Swisscom private customer connections are unsuitable for operating your own mail server. This is because Swisscom redirects all tcp4/25 connections via an SMTP proxy and your mail server only ever communicates with the outside world via this (see [https://www.swisscom.ch/p25](https://www. swisscom.ch/p25)). Additionally, your public IP’s reverse DNS record will almost certainly not match the hostname you configured on the mail server, which can lead to further problems.

      Your domain host probably runs a so-called smart host, through which you can send emails from your domain and then set SPF records accordingly, for example.

    Swisscom private customer connections are unsuitable for operating your own mail server. This is because Swisscom redirects all tcp4/25 connections via an SMTP proxy and your mail server only ever communicates with the outside world via this (see [https://www.swisscom.ch/p25](https://www. swisscom.ch/p25)). Additionally, your public IP’s reverse DNS record will almost certainly not match the hostname you configured on the mail server, which can lead to further problems.

    Your domain host probably runs a so-called smart host, through which you can send emails from your domain and then set SPF records accordingly, for example.

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    Have you tried turning it off and on again?

    @kaiserm I don’t know whether the smart host operator creates an “archive copy” of every email that is forwarded, but it would definitely be possible. I also doubt that a pair of human eyes will read all your messages, but that would also be possible in principle.

    Due to its principle, email is an insecure communication medium, i.e. You can listen in pretty much anywhere; both on the servers and between them during transmission if this is unencrypted. Although the latter now only affects a small proportion of all mail servers (see Statistics from Google), the rule of thumb still remains that the level of confidentiality of email Mail is about the same as a postcard.

    End-to-end encryption would also provide a solution here, e.g. with PGP/GPG or S/MIME. Unfortunately, this never became widely accepted because it was too complicated and cumbersome.

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    Have you tried turning it off and on again?

    @“x”#38531Hmm… yes. Thanks again for your help. I just try to keep the risks as small as possible, but as you already wrote, the medium itself is unfavorable. I have already tested PGP, but the implementation is sometimes quite complex. That’s why I also created a ProtonMail address. Anyway, my domain provider offers a smart host solution that I will now take a closer look at. Thanks!

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