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How to diagnose "550 No Such User Here"

Axel Cervera
  • Updated

Introduction

 

If senders are reporting bouncebacks with this failure message when sending to an address in your server, you may solve the issue by checking a few things that are the most common causes.

 

Procedure

 

First of all, you will want to ensure that the DNS for the domain resolves to the server you intend on receiving email to.

 

  • To do so, you may use "dig" to perform DNS lookups and obtain the MX records. 
 dig $DOMAIN +short MX

 

 Make sure that the IP address of the MX record(s) resolve to the correct server:

 

 dig $MX_RECORD +short A

 

If the DNS records are valid, you will next want to ensure that the domain's email routing path is correctly set. If you are receiving email to the server locally, then you will want to make sure that the routing is configured to "Local."

 

    • Checking via the command line:
 grep -H '^$DOMAIN' /etc/{remote,local}domains 

 

Make sure that file permissions are correctly configured. If specific files do not have enough permissions or ownership, you may also be seeing this failure. 

    • You may use the following cPanel provided script that reviews and fixes any permission issues with email-related files: 
  /scripts/mailperm --verbose $CPANEL_USER 
    • Check the permissions for the user's home directory.
      • If FileProtect is enabled:
        • The user’s /home/$username/ directory will be set to 0711 permissions.
      • If FileProtect is disabled:
        • The user’s /home/$username/ directory will be set to 0755 permissions.

FileProtect Documentation

 

If you are using a server that makes use of an email relay/Smarthost, make sure that the configuration is properly setup.

  • Home » Service Configuration » Exim Configuration Manager » Basic Editor » Smarthost support.

 

 

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