$ sudo exim -bp | head -n 2
21d  5.2K 1YU9Ma-0007Ow-Hf <xx@xxx.com>
          xxx@yahoo.com

$ sudo exim -brt yahoo.com
Retry rule: *  *  F,2h,15m; G,16h,1h,1.5; F,4d,6h;

$ zgrep 1YU9Ma-0007Ow-Hf /var/log/exim4/mainlog*
/var/log/exim4/mainlog:2015-03-27 12:54:09 1YU9Ma-0007Ow-Hf == xxx@yahoo.com routing defer (-51): retry time not reached
/var/log/exim4/mainlog:2015-03-27 12:54:13 1YU9Ma-0007Ow-Hf == xxx@yahoo.com routing defer (-51): retry time not reached
/var/log/exim4/mainlog:2015-03-27 14:41:16 1YU9Ma-0007Ow-Hf == xxx@yahoo.com routing defer (-51): retry time not reached
/var/log/exim4/mainlog:2015-03-27 14:42:08 1YU9Ma-0007Ow-Hf == xxx@yahoo.com routing defer (-51): retry time not reached
/var/log/exim4/mainlog:2015-03-27 14:43:23 1YU9Ma-0007Ow-Hf == xxx@yahoo.com routing defer (-51): retry time not reached
/var/log/exim4/mainlog.1:2015-03-26 13:52:25 1YU9Ma-0007Ow-Hf == xxx@yahoo.com routing defer (-51): retry time not reached
...

exim -Mrm <message-id>