Outlook adds additional line breaks in plain text emails

[Drakanor]

I'm fighting with a strange problem sending plain text emails with Java. Outlook (2003 and 2007) adds additional line breaks throughout the mailtext. Every other mail client I tested show the email as intended.

First I thought Outlook would not interpret \n correctly and did line breaks with \r\n, but that didn't help either. Also, the email is encoded by quoted printable and UTF-8.

Here an example:

"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut vestibulum interdum diam, ut venenatis augue ultrices sit amet. Nunc iaculis dignissim ultricies. Nunc id enim vel metus dictum tincidunt. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Nam luctus ante vitae est eleifend aliquam. Sed in metus quis ipsum porta iaculis id eget dolor. Cras venenatis ipsum et mauris molestie porta. Nulla facilisi.

Donec nisl lacus, ultrices et egestas eu, fringilla viverra arcu. Etiam rutrum, neque nec ornare mattis, arcu ligula gravida nulla, at adipiscing sapien lorem sed massa. Nulla a nisl eget purus pretium condimentum. Pellentesque urna dolor, viverra ut gravida nec, ultricies vitae magna. Etiam in auctor libero. Pellentesque rutrum gravida feugiat. Praesent arcu mi, dapibus non viverra et, auctor dignissim lectus. Curabitur semper augue non libero blandit volutpat. Aenean por
 ttitor porttitor ligula, in faucibus mauris tempor vitae. Proin felis lectus, ultricies nec facilisis nec, porttitor sit amet metus. Vestibulum ut leo arcu."

After 948 chars Outlook is adding a line break which breaks the word "porttitor". No matter how many line breaks I manually add in between, Outlook always does these line breaks by itself.

I'd really appreciate any hints, I'm clueless right now.

Thanks,
Roman