You suddenly realize that the emails on your server are not working and the mail logs shows the following messages:

1MnfEt-0007pQ-Tn == xyz@abc.com R=defer_router defer (-1): All deliveries are handled by MailScanner
1MnfBw-00037y-9h == abc@xyz.com R=defer_router defer (-1): All deliveries are handled by MailScanner

This mostly happens when Mailscanner is not working properly as all deliveries are handled by MailScanner. To fix the issue, restart your mail service first i.e.

service exim restart

then, start the Mailscanner executing the following command:

/usr/mailscanner/bin/check_mailscanner

If it displays any PIDs, kill them and execute the command again. This will start your MTA and MailScanner which will make sure your emails start working again.} else {