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Re: using the character @ in the local part

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  • Reindl Harald
    ... and if this is the reason it proves why it is a stupid idea to use special chars one more time ANY hop from the users MUA to the final destination must
    Message 1 of 31 , Jan 3, 2013
      Am 03.01.2013 22:03, schrieb martijn.list:
      > On 01/03/2013 09:48 PM, Michael Blessenohl wrote:
      >> I'm sorry, I'll try not to use my smartphone again to answer mails from
      >> this list.
      >>
      >> I ment using a remote machine as client to connect to the postfix server
      >> as opposed to connect to the machine itself. I don't know why it does
      >> matter, but apparently it does. Using the hostname, IP or localhost
      >> makes no difference at all. That's the same for me.
      >
      > Are you connecting through some kind of firewall which intercepts the SMTP connection, for example a CISCO PIX with
      > SMTP fixup enabled?

      and if this is the reason it proves why it is a stupid
      idea to use special chars one more time

      ANY hop from the users MUA to the final destination
      must handle sender / rcpt the same way, if ANY of the
      involved servers / appliances treats it as invalid
      you have lost the game

      ignore these facts and still use special cars means mail-roulette
      your users will not be thankful if you point to RFCs which states
      you are right if it does not work in their real life
    • 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
        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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