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using the character @ in the local part

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  • Michael Blessenohl
    Hi, I tried using an e-mail address @ @example.com in postfix. When I try to deliver a mail to it, postfix rejects it with the error message 501 5.1.3 Bad
    Message 1 of 31 , Jan 2, 2013
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      Hi,

      I tried using an e-mail address "@"@... in postfix. When I try
      to deliver a mail to it, postfix rejects it with the error message

      501 5.1.3 Bad recipient address syntax (state 13)

      I defined an alias, so in theory it should work. The recipient address
      is totally valid as far as I know and as far as online validators tell.


      Thanks for any hints.
      Blessenohl
    • Wietse Venema
      ... Come on, don t be so naive. The backup MX scenario is an EXAMPLE of how @ in local-part can result in trouble. The same problem may happen in ANY piece of
      Message 31 of 31 , Jan 4, 2013
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        Michael Blessenohl:
        > The security issue is, as far as I understand, that a backup MX uses an
        > @ in the local part for internal purposes. Which, in theory, can be
        > exploited to use the server as open relay. As long as I don't use a
        > backup MX, I don't have an open relay and everything is fine, isn't it?

        Come on, don't be so naive. The backup MX scenario is an EXAMPLE
        of how @ in local-part can result in trouble. The same problem may
        happen in ANY piece of software that decisions based on the content
        of an email address.

        Wietse
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