Version: (using KDE 4.2.1) OS: Linux Installed from: Fedora RPMs If you activate "Option/Formatting (HTML)" in mail compose window this option get saved. Then if you get an invitation and accept it, the reply is send as multipart mail with plain text and HTML. But the recipient Kontact just displays the code of the vcalender item - the user ist not able to add it to his event.
seems to be fixed http://websvn.kde.org/?rev=964280&view=rev and http://websvn.kde.org/?rev=970739&view=rev sad that i not even got a reply :( after i could confirm that it's resolved i'll close this bug.
I'll close this for you Julian, since you say it works now. If the bug still happens for you please reopen.