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[resolved] 503 5.5.1 Error: nested MAIL command (4 posts)

  1. bjou
    Member
    Posted 2 years ago #

    Hi,

    I think I found a bug in the Subscribe2 plugin (or maybe it is in the WP Mail SMTP, maybe you can help figuring it out).
    After many hours of investigation of the mailserver logs and the tcp streams I found that, as soon as there seems to be a unresolvable domain in the RCPT TO, the script behaves odd. Please see the protocol:

    220 mymailhost.de ESMTP mymailhost.de
    EHLO http://www.mydomain.de
    250-mymailhost.de
    250-PIPELINING
    250-SIZE 100145600
    250-VRFY
    250-ETRN
    250-STARTTLS
    250-AUTH PLAIN LOGIN
    250-AUTH=PLAIN LOGIN
    250-ENHANCEDSTATUSCODES
    250-8BITMIME
    250 DSN
    AUTH LOGIN
    334 XXXXXXX
    XXXXXXX==
    334 XXXXXXX
    XXXXXXX
    235 2.7.0 Authentication successful
    MAIL FROM:<noreply@mydomain.de>
    250 2.1.0 Ok
    RCPT TO:<noreply@mydomain.de>
    250 2.1.5 Ok
    RCPT TO:<xxx@googlemail.com>
    250 2.1.5 Ok
    ...many more mail addresses
    ...many more mail addresses
    ...many more mail addresses
    ...many more mail addresses
    RCPT TO:<xxx@hotmail.com>
    250 2.1.5 Ok
    RCPT TO:<xxx@yahoo.de>
    250 2.1.5 Ok
    RCPT TO:<xxx@20002live.cn>
    450 4.1.2 <xxx@20002live.cn>: Recipient address rejected: Domain not found
    RCPT TO:<xxx@hotmail.com>
    250 2.1.5 Ok
    MAIL FROM:<noreply@mydomain.de>
    503 5.5.1 Error: nested MAIL command
    MAIL FROM:<noreply@mydomain.de>
    503 5.5.1 Error: nested MAIL command
    MAIL FROM:<noreply@mydomain.de>
    503 5.5.1 Error: nested MAIL command
    MAIL FROM:<noreply@mydomain.de>
    503 5.5.1 Error: nested MAIL command
    MAIL FROM:<noreply@mydomain.de>
    503 5.5.1 Error: nested MAIL command
    MAIL FROM:<noreply@mydomain.de>
    503 5.5.1 Error: nested MAIL command
    MAIL FROM:<noreply@mydomain.de>
    503 5.5.1 Error: nested MAIL command
    MAIL FROM:<noreply@mydomain.de>
    503 5.5.1 Error: nested MAIL command
    MAIL FROM:<noreply@mydomain.de>
    503 5.5.1 Error: nested MAIL command
    MAIL FROM:<noreply@mydomain.de>
    503 5.5.1 Error: nested MAIL command

    This mail does NOT get send because of the many errors at the end. If the unresolvable domain is not listed here, then the mail gets send perfectly.

    Conclusion: If there are unresolvable domains, the script tries to add ANOTHER "MAIL FROM" at the end, but "MAIL FROM" is already set at the beginning, so there are multime "MAIL FROM" and the postfix does not accept this (nested command), which is wise, because there can only be one MAIL FROM).

    If there is no unresolvable domain, there are NO additional "MAIL FROM" at the end.

    How can we fix this in the code?

    -best regards, Bjoern

    http://wordpress.org/extend/plugins/subscribe2/

  2. mattyrob
    Member
    Plugin Contributor

    Posted 2 years ago #

    @bjou,

    I've done a few googles on this and it seems linked perhaps to a glitch in the 'amavisd' binary on the server. (So, much further down the line than plugins, WordPress or PHP even)

    Your server should ideally have a build of amavisd-new as other branches are poorly maintained. can you check this with your hosting provider?

  3. bjou
    Member
    Posted 2 years ago #

    Hey Matty, thanks for your feedback, I also found these amivisd problems and already asked my provider: amivisd is not(!) in use and I can reproduce the error as described above.

  4. mattyrob
    Member
    Plugin Contributor

    Posted 2 years ago #

    @bjou,

    Are your hosting providers running any software between scripting level and the mail binary? Spam checkers or virus scanners for example.

    While amivisd has been a culprit like this before it was only because it operates in that layer.

    One check you might be able to do is to attempt to recreate this issues by directly calling the mail() function in a PHP script. That would exclude WordPress, the PHPMailer library or any plugins as the source of the issue.

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