I'm experencing Message-ID munging problems with the Debian packages of 20060704a. I'm seeing some messages come through with a second Message-Id field added which contains only a comment.
This appears to happen because other programs are generating a field called Message-ID while CRM114 is trying to munge a field called Message-Id. This upsets at least mutt (which looks like it will accept either capitalisation), causing it to think that the Message-ID contains only a comment.
I feel mutt is being reasonable here: it's being liberal in what it accepts and getting confused because crm114 is being liberal in what it generates. As previous discussion notes the problem could be avoided if crm114 were to avoid generating a null message ID but you may also wish to consider trying to munge both upper and lower case variants of the field.