Fixed EXIM Error : all hosts for 'domain.tld' have been failing for a long time (and retry time not reached)

An error encountered on private email serversWhen they try to send e-mail from a specific area or a specific email address.
The scenario is quite simple.
We have a private e-mail address (ie it does not belong to Gmail, MSN, OutLook, iCloud, Yahoo !, etc.) from which we cannot send messages to another private email address. The message returned will be:

A message sent you That Could not Be Delivered to one or more of STI
containers. This is a permanent error. The following address (es) failed:
mail_destinatar@domain.tld
all hosts for 'domain.tld' have been failing for a long time (and retry time not reached)

In most situations this error It occurs when database "Exim Retry" It is corrupt. So the problem is The server that is trying to send the message.

resolving error consists Exim delete Retry Database si restarting the EXIM service server.

Perform the following server command line to delete database Exim Relay:

cd /var/spool/exim/db
rm -f retry retry.lockfile
rm -f wait-remote_smtp wait-remote_smtp.lockfile

After executing these commands that will delete the files: retry, retry.lockfile, wait-remote_smtp and wait-remote_smtp.lockfile, restart the "exim" service.

service exim restart

To execute these commands you must have access to the server console (or SSH access) and sufficient permissions.