Exim Bounce Error

Exim Bounce Error : retry time not reached for any host after a long failure period

The problem is NOT about dns or anything else.
Because as you can see from that log. Server gives "after a long failure period" error in the same second after we send the mail.

Cause: your exim db files are corrupted.
Solution:

go to

/var/spool/exim/db

and delete files: retry , retry.lockfile , wait-remote_smtp, wait-remote_smtp.lockfile

restart exim.