[Typo3] CSS code added at the end of Newsletter

[christian oettinger]

maybe a silly question:

A last I have a working Newsletter styled with CSS. This is no problem 
for me, as it works without CSS too (so CSS is just additional). 
Everyhing is all well besides from the fact, that some webmail providers 
show the unstyled version of he newsletter (which is fine) and add the 
CSS code at the bottom (which is awful).

How can I prevent this?
has this anything to do with my template?


thanks for hints!

oe