This depends strongly on your eGroupware Version.
If you use 1.4 its likely to happen, since most of copy and paste text will
not pass
the Test on secure content.
If it is 1.6. it should work, as felamimail tries to suspect if it retrieves
an empty post for the mailbody
that content regarded as dangerous may be the cause, retrieves the text, and
tries to clean it.
If it is 1.4 you need to update.
If it is 1.6 I need to test, and look into the issue.