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Unable to send mails when "Discard and send an error to the sender" is selected

Discussion in 'E-mail Discussion' started by tui, Apr 14, 2018.

  1. tui

    tui Well-Known Member

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    Hello,

    I found a strange problem with a email account:

    I created a no-reply@domain.com account, (because i want to send mails from this account with smtp auth)

    I created a forwarder for this account (no-reply@domain.com) to destination "Discard and send an error to the sender (at SMTP time) and put my custom failure message "This account is not configured to receive emails, please contact us" (i also use the default failure message "no such person at this address" for testing purposes).

    Using this forwarder (Discard and send error) we are unable to send mails from smtp clients from this account because our smtp cpanel server send us a sender verify failed > "this account is not configured to receive mails" or "no such person at this address" but we can send mails from webmail... only smtp is not working

    However if we change the forwarder destination to "Discard (Not Recommended)" we can send mails from our smtp clients without any problems....

    The account actually exist so sender verify failed should not fail,

    As the name of the account says, this is a no-reply mail that we are going to use to send notifications to our users, but they are users and there is always more than one lackadaisical that reply mails so we do not want to use "Discard (Not Recommended)" because they will send a mail and wait for response, so we want to use "Discard and send error" so they can react that it was a no-reply email and use our contact channels...

    I think that this is a bug but im not sure if it is a cpanel bug or exim bug... because the account actually exist and smtp threat it as inexistent (sender verify failed) when use "discard and send error" but not when use "Discard" (without error)

    What do you think?
     
  2. cPanelMichael

    cPanelMichael Technical Support Community Manager
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    Hello,

    Can you let us know the output from /var/log/exim_mainlog when attempting to send a message via the SMTP client? EX:

    Code:
    exigrep "MSGSUBJECT" /var/log/exim_mainlog
    Replace "MSGSUBJECT" with the subject of the test message.

    Thank you.
     
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  3. tui

    tui Well-Known Member

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    Hello,

    I tried to get the output of exim_mainlog but there is no output when "Discard and send error" forward is enabled but here is my smtp client log:


    Code:
    2018-04-16 18:48:41 SERVER -> CLIENT: 220-smtpcpanelserver.domain.com ESMTP Exim 4.89_1 #1 Mon, 16 Apr 2018 13:49:25 -0500 220-We do not authorize the use of this system to transport unsolicited, 220 and/or bulk e-mail.
    2018-04-16 18:48:41 CLIENT -> SERVER: EHLO smtp-client-hostname
    2018-04-16 18:48:41 SERVER -> CLIENT: 250-smtpcpanelserver.domain.com Hello smtp-client-hostname [XXX.XXX.XXX.XXX]250-SIZE 52428800250-8BITMIME250-PIPELINING250-AUTH PLAIN LOGIN250 HELP
    2018-04-16 18:48:41 CLIENT -> SERVER: AUTH LOGIN
    2018-04-16 18:48:41 SERVER -> CLIENT: XXX XXXXXXXXXXX
    2018-04-16 18:48:41 CLIENT -> SERVER: <credentials hidden>
    2018-04-16 18:48:41 SERVER -> CLIENT: XXX XXXXXXXXXXX
    2018-04-16 18:48:41 CLIENT -> SERVER: <credentials hidden>
    2018-04-16 18:48:41 SERVER -> CLIENT: 235 Authentication succeeded
    2018-04-16 18:48:41 CLIENT -> SERVER: MAIL FROM:<user@domain.com>
    2018-04-16 18:48:41 SERVER -> CLIENT: 250 OK
    2018-04-16 18:48:41 CLIENT -> SERVER: RCPT TO:<user@hotmail.com>
    2018-04-16 18:48:41 SERVER -> CLIENT: 550-Verification failed for <user@domain.com>550-No such person at this address.550 Sender verify failed
    2018-04-16 18:48:41 SMTP ERROR: RCPT TO command failed: 550-Verification failed for <user@domain.com>550-No such person at this address.550 Sender verify failed
    2018-04-16 18:48:41 CLIENT -> SERVER: QUIT
    2018-04-16 18:48:41 SERVER -> CLIENT: 221 smtpcpanelserver.domain.com closing connection
    SMTP Error: The following recipients failed: user@hotmail.com: Verification failed for <user@domain.com>No such person at this address.Sender verify failed
    Mailer Error: SMTP Error: The following recipients failed: user@hotmail.com: Verification failed for No such person at this address. Sender verify failed 
     
  4. cPanelMichael

    cPanelMichael Technical Support Community Manager
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    Hello,

    If the remote mail server is rejecting the message, it's generally because the remote mail server was unable to verify the email address you are sending "from". Some mail servers will reject messages due to failed attempts to verify the sending email address is valid. In this case, it looks like you have configured the cPanel server to reject email messages messages sent to "user@domain.com", and thus Hotmail considers that a verification failure. As a workaround, you could remove the forwarder and instead setup a custom filter rule for that email account that discards messages instead of rejecting them.

    Thank you.
     
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  5. tui

    tui Well-Known Member

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    Hello, but no, you are wrong, the cpanel server is the server that is refuse to send the email not the remote server, the error message is from the cpanel server not from hotmail (the mail does not even leave the server and also i use some custom domains, yahoo, apple and other email accounts all with same result, its something on cpanel server that has a bug), if i use discard message (without error) i can send mail without problems... in resume:

    Using Discard and send error forward, cpanel server refuse to send the mail from smtp but it allow to send mail from webmail
    Using Discard (without error) forward, cpanel server allow to send mail without any problem from smtp and from webmail
     
  6. cPanelMichael

    cPanelMichael Technical Support Community Manager
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    Hello,

    If it's the cPanel server rejecting the message delivery attempt, then there are two options under the "Mail" tab in "WHM >> Exim Configuration Manager" that you can temporarily disable to verify if they are the culprit:

    Sender Verification Callouts
    Sender Verification


    If disabling those options allow the email to deliver, then you would need to whitelist the IP addresses of the senders you'd like to let bypass that restriction using the following option under the "Access Lists" tab in "WHM >> Exim Configuration Manager":

    IP addresses for which to bypass SMTP-time sender verification checks

    You may also want to see if anything is logged to /var/log/exim_rejectlog when this happens to get a better idea of why exactly it was blocked.

    Thank you.
     
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  7. tui

    tui Well-Known Member

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    Hello,

    Its not possible to add the IP addresses of the senders (i even dont know the ip addreses... all clients have dynamic ip's)....

    I opened a ticket for this (ID 9443431) and a case ID was filled (CPANEL-19829), so it seems that it was a bug at the end, my cPanel Technical Analyst was able to replicate the behavior on my server and on his test servers too,

    i just hope that a patch gets pushed out soon :)

    Thanks Michael
     
  8. cPanelMichael

    cPanelMichael Technical Support Community Manager
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    Hello @tui,

    Thank you for taking the time to open the support request. I can confirm that internal case CPANEL-19829 is now open to address an issue where creating an email forwarder with ":fail: No such person at this address" as the destination address blocks remote SMTP connections to the email account (despite it working with Webmail applications). I'll monitor this case and update this thread with more information as it becomes available.

    Thank you.
     
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