Hello,

> OK, I lied.  All of the signatures were good except for two messages
> from Jean-Christophe:  
> 
> 20160921191202.GB18462@lovelace.schplaf
> 20160921195336.GD18462@lovelace.schplaf
> 
> Both of those were bad.  The first of his was good:
> 
> 20160921060257.GB29391@minitel.priv.enst-bretagne.fr

Exactly, the main difference is the fact I did not use the same computer
to send the emails. In both cases, I have custom headers (for instance
this email should also have custom headers). I did tests with my
different addresses, different keys and different computers. Only my
personal computer "generates" the error.

JC