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Thread: Error when telnet used for testing

  1. #1
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    Default Error when telnet used for testing

    I am using Putty to try to access Zimbra using telnet to port 25. After the initial
    220 xxxxx ESMTP Postfix

    typing in
    HELO test.com
    produces an error:
    502 5.5.2 Error: command not recognized

    Repeating the HELO command straight away is successful and I can then proceed to send an email. Any ideas why there is an initial error or suggestions where to look to get an answer?

    Thanks

  2. #2
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    Does the same happen if you perform the telnet directly on the server ? When you perform the telnet are you going through a firewall at all ? When you get the initial connection if you hit return and then helo xyz.com does it work ?

  3. #3
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    Performing a telnet on the server does not give the error.
    Yes, we go through an old 3com Superstack III to get to the DMZ where the mail server sits.
    Hitting a return on connection produces the error, then the helo test.com works fine.

  4. #4
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    Personally I feel that it is your switch which is munging the initial connection. This behavior has been seen elsewhere Postfix outside network 220 response and EHLO - LinuxQuestions.org.

  5. #5
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    Just found that when using putty to access Zimbra using Raw rather than Telnet on port 25, the error doesn't occur!

  6. #6
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    Still reckon its your switch

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