http alert mail as octet-stream

Hi,

I'm using xymon 4.3.11 on Scientific Linux 6.4

I discovered a weird phenomenon with the alert mails that xymon is sending. Most mails are coded as text/ascii by my postfix MTA. Only the mails about http alerts are sent base64 encoded, because the content is regarded as an octet-stream. I had no idea why this happened, because the mails look normal as being ascii code. But when I used a script to store the message, I found out, that all lines of the http message are terminated by a ctrl-m character:

BBALPHAMSG=myhost.xyz.de:http red [621842]
red Fri Oct 11 09:43:45 2013: Not Found

&red http://myhost.xyz.de/myurl - Not Found

HTTP/1.1 404 Not Found^M
Date: Fri, 11 Oct 2013 07:43:45 GMT^M
Server: Apache/2.2.22 (Ubuntu)^M
Vary: Accept-Encoding^M
Content-Length: 308^M
Connection: close^M
Content-Type: text/html; charset=iso-8859-1^M

Seconds:     0.00


Where does this happen and how can I change the behaviour?

Thanks,
Dirk