What is the best way to restrict postfix senders in Zimbra 8 so that users cannot send using a FROM address other than their own?

I've tried modifying the instruction here:...

I am am using the Zmailbox class to create a calendar event. Everything works fine except...The event is created as plain text even though I put the content type as "text/html". Can anyone please...

We are having an issue with emails leaving our system with a forged FROM address. Is there anyway to force Zimbra to limit the from address to specific domains?

When pushing notes in CarDav format to the iPhone Zimbra seems to truncate longer notes. Any ideas on how I would fix this?

I am able to get cardDAV support working to the point of an initial sync with Zimbra, but when I update/add a contact (phone or PC) the two never sync back up again. Any ideas what I might be missing?

I have a user who wants to be able to open a message full-screen, move it to a folder/delete it and then have Zimbra automatically move to the next message in full screen. Is this possible with...