Comment 2 for bug 265625

I've found it. A fast fix for is to comment lines 149-150
in Mailman/Handlers:/CookHeaders.py:

--- CookHeaders.py 2002-05-02 14:51:36.000000000 +0200
+++ CookHeaders.py.new 2002-05-02 16:12:09.000000000 +0200
@@ -146,8 +146,8 @@
         # Wrap these lines if they are too long. 78
character width probably
         # shouldn't be hardcoded, but is at least
text-MUA friendly. The
         # adding of 2 is for the colon-space separator.
- if len(h) + 2 + len(v) > 78:
- v = CONTINUATION.join(v.split(', '))
+# if len(h) + 2 + len(v) > 78:
+# v = CONTINUATION.join(v.split(', '))
         msg[h] = v
     # Always delete List-Archive header, but only add it
back if the list is
     # actually archiving

Tested with Mailman 2.1b1, Source Mage GNU/Linux 2.4.18,
Postfix 1.1.7.
I know there should be a better way, but I'm not a Python
programmer at all. :)