I've hit the problem similar to the one reported in the past (#573936).
Milter-greylist segfaulted:
Aug 26 00:17:53 mx1 kernel: [2459462.551205] milter-greylist[3223]: segfault at a0 ip b772e8a0 sp b5578320 error 4 in libmilter.so.1.0.1[b7724000+d000]
When it was started again, I've noticed following error in logs:
Aug 26 00:26:09 mx1 milter-greylist: unknown token "[" line 17332, skipping
Aug 26 00:26:09 mx1 milter-greylist: dump error at line 17332: syntax error
Unfortunately, I didn't check the database entry at that time and I can't find
it now.