Outbound mail issue when recipient domain not found

Discussion in 'Server Operation' started by mcisar, Mar 5, 2022.

  1. mcisar

    mcisar New Member HowtoForge Supporter

    I have a server running ISPConfig using one of the Perfect Server Centos 7 configurations w/Postfix. I have a client who has an email account on the server which they use to mail out statements and invoices from their accounting software. They've been having some problems in that the send just stops randomly. I've been watching the mail logs for the past couple of months as they are running the statements and we have determined that the problem seems to be happening if they have an email address on a customer account that has an invalid domain name. Having a mis-spelled user part doesn't seem to be an issue because that goes through to the customer's mail server and then is bounced back as invalid from the far side. Obviously the accounting software is just not properly handling receiving the 450 4.1.2 domain not found error while it's sending... but who knows when/if the vendor will fix the issue.

    I'm just wondering if anyone knows if there's any configuration that could be changed within Postfix that would allow it to not validate the recipient domain in the "interactive" part of the mail session ... but rather accept the message/recipient for processing and then bounce it back to the sender instead in the same way as an invalid email address?
  2. Jesse Norell

    Jesse Norell ISPConfig Developer Staff Member ISPConfig Developer

    You would need to change smtpd_recipient_restrictions, or maybe there is a whitelist already setup in it, I can't check right now.

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