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SMTP: Invalid response code received from server (code: 421, response: Unexpected failure, please try later

SMTP: Invalid response code received from server (code: 421, response: Unexpected failure, please try later

Description:

While sending mail from email Id create from cpanel server getting the below error,

SMTP: Invalid response code received from server (code: 421, response: Unexpected failure, please try later.
Invalid response code received from server
Solution:

– Root cause for the issue is that mismatch of the exim configuration file.

– Follow the below steps to retrive the default configuration file .

– Download the existing exim configuration file from whm.Login to whm with root login details and click on service configuration and select Exim configuration Manager then Backup.

Service Configuration -> Exim Configuration Manager -> Backup

Invalid response code received from server01

– Once backup configure we have to reset the exim configuration in default settings.

Service Configuration -> Exim Configuration Manager -> Reset

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– From reset menu check the options mention the drop down.

Reset the entire Exim configuration to the default settings provided with cPanel & WHM

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– In some cases database will also corrupt.Run the following command ,

mysqlcheck -r eximstats

–  And check the selinux status enabled or disabled in the server.

– Now restart the exim services using below command

service exim restart

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