MailEnable: Message could not be delivered to some recipients: SMTP Server Returned: 450 4.7.1

Created:

2016-11-16 12:46:08 UTC

Modified:

2017-04-24 11:23:38 UTC

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MailEnable: Message could not be delivered to some recipients: SMTP Server Returned: 450 4.7.1

Applicable to:

  • Plesk 12.5 for Linux
  • Plesk 11.0 for Windows
  • Plesk 11.5 for Windows
  • Plesk 12.5 for Windows

Symptoms

Emails bounced back with the following delivery failure description:

MailEnable: Message could not be delivered to some recipients.
...
Reason: Remote SMTP Server Returned: 450 4.7.1 Client host rejected: cannot find your hostname

Cause

MailEnable misconfiguration.

Resolution

  1. Check the "Default mail domain name" setup in MailEnable:

    • Open MailEnable Management > Servers > localhost > connectors > SMTP > right click to open Properties .

    • Switch to the General tab > check "Default mail domain name", say you have the mail.mydomain.com specified.

  2. Make sure that the mail.mydomain.com can be reversed correctly. Do the following test:

    > nslookup mydomain.com
    Server: 8.8.8.8
    Address: 8.8.8.8#53

    Non-authoritative answer:
    Name: mydomain.com
    Address: A.B.C.D

    > nslookup A.B.C.D
    Server: 8.8.8.8
    Address: 8.8.8.8#53

    Non-authoritative answer:
    E.F.G.I.in-addr.arpa name = ns1.otherdomain.com

    Authoritative answers can be found.

    > ping ns1.otherdomain.com
    ping: unknown host ns1.otherdomain.com

    The output above shows that host IP reverse lookup test fails.

    This test checks all the local machine's TCP/IP addresses for reverse DNS lookup. Some mail servers perform a reverse lookup on you IP address. You need to ensure that external IP addresses facilitate a reverse lookup or mail servers (like Yahoo and Hotmail) will reject your mail.

  3. Additionally please run the "%plesk_dir%\\Mail Servers\\Mail Enable\\Bin\\MEDIAG.exe" - tool that will show you the diagnostic report. This utility is designed to assist you in configuring MailEnable. It validates your configuration and assists you in configuring MailEnable services.

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