I thought that thunderbird respected the usual File Associations settings that you can set in systemsettings. I think that is what I used, but maybe I'm thinking of chrome. Michael <div class="gmail_quote"> On Wed, Oct 5, 2011 at 1:23 PM, Hugo Coolens <<a href="mailto:coolens@kahosl.be">coolens@kahosl.be</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"> When I have an e-mail with a docx-document as an attachment, thunderbird automatically opens LibreOffice when I click the attachment, when I have however a doc-document I get a an error when clicking on the attachment, like this: /tmp/OPDOC24082005-1.doc could not be opened, because the associated helper application does not exist. Change the association in your preferences. So I'd like to add the .doc file extension and have LibreOffice open it too but I can't find out how to do it in Thunderbirds Preferences-->Attachments. I'm missing an add Content Type-possibility. Maybe someone here knows which file I should change manually and how to add a rule for .doc-documents? regards, hugo p.s. 1 I'm using Kubuntu Natty Narwal p.s. 2 When I right click on the attachment-document I don't get a drop down box, so I can't choose an application that way neither -- kubuntu-users mailing list <a href="mailto:kubuntu-users@lists.ubuntu.com" target="_blank">kubuntu-users@lists.ubuntu.com</a> Modify settings or unsubscribe at: <a href="https://lists.ubuntu.com/mailman/listinfo/kubuntu-users" target="_blank">https://lists.ubuntu.com/mailman/listinfo/kubuntu-users</a> </blockquote></div>