[exim] recurring db problem

On *work* system we are seeing messages like this:


2014-09-24 17:48:59 1XWpkP-0004Oc-Ol Berkeley DB error: PANIC: fatal
region error detected; run recovery
2014-09-24 17:48:59 1XWpkP-0004Oc-Ol Berkeley DB error: page 1: illegal
page type or format
2014-09-24 17:48:59 1XWpkP-0004Oc-Ol Berkeley DB error: PANIC: Invalid
argument
2014-09-24 17:48:59 1XWpkP-0004Oc-Ol Berkeley DB error:
/var/spool/exim/db/retry: pgin failed for page 1
...

The cure is to shut down exim, delete everyting in /var/spool/exim/db/ls
then restart exim, but an hour later (while processing apparent spam) it
started up again. Disc space not running out.

So: Bug in exim or bdb. But possibly triggered by spam?

==John ffitch