[Hampshire] Debugging pipes

Hi,

I have an email system based on fetchmail->exim->cyrus-imap.
Some emails get caught in the queue and never get delivered.
It appears that the process in cyrus-imap receiving the email crashes.
Unfortunately, I do not get any stack trace or any information as to
why it failed.
If I run exim and cyrus-imap inside gdb, this also does not help, as
the process used to do the receive into cyrus looks like a fork or
exec from the cyrus-imap process, and gdb does not attach to them.

Does anyone have any idea of how I can track this down a bit more?

James