[Mailman-Users] mailman headers get corrupted / incomplete

[wally b]

Hi,

Since I updated my server (ubuntu, mailman with exim) it seems that mailman does not send the complete mail headers.
Some mail clients can not interpret and display the mails correctly and show mails like this:

���8�}��ox�M�{^���鮖ةj�j[^�v�������j����^1��ۀ��a6�A�

Maybe I found the cause of this:
(last part of) the headers look like this:

....
X-SA-Exim-Scanned: No (on b(0, 0, =
0);" class=3D""><span style=3D"font-kerning: none" class=3D"">Als u zich =
wilt afmelden voor deze emails, laat ...
....


The text "..b(0,.." etc seems not to belong there. This is some text that is somewhere else in the mail and is copied over this part.
I expect this line to be:

X-SA-Exim-Scanned: No (on pknpserver.pknpapendrecht.nl); SAEximRunCond expanded to false

How can this happen?
Please help me to find out how this can occur.

Regards,
T