queue run: process 123 crashed with signal 11 while delivering 1AbcD2-3456E7-8F

If you get errors in your /var/log/exim/mainlog or paniclog looking similar to this:

queue run: process 123 crashed with signal 11 while delivering 1AbcD2-3456E7-8F

It means that exim is generating a segfault.   It's not too likely that the exim code is at fault, but more likely at the it's a binary issue where the binaries may have been compiled against different libraries than the ones you're using.

To resolve the issue, recompile exim from source.