I have tried various settings in Word 2013 options (general - allowing opening of outlook attachments editable) and trust center (disabling various untrusted item restrictions) and also adding entire root drives and subfolders and internet and download folders as trusted.
Still all Word attachments from email received in Zimbra open read only unless you download them first and open them directly in word.
Any way to open an attachment of word, excel, powerpoint directly by clicking on it and be editable.