Hello,
As a further addendum to this topic I've found that this behavior begins
with version 6.1.3. Versions prior to this do not seem to give the
"incorrect header" error messages.
From reading the NEWS files I suspect that it has something to do with
the "end-of-header bulletproofing" but I will leave any further
investigation to those who know what they're doing with the fetchmail
code if this is viewed as a problem. On the other hand, if the
"incorrect header" messages are generally viewed as a "good thing" then
so-be-it.
Regards, Mike Klinke