Ken Murchison murch at
Tue Dec 16 22:35:56 EST 2014

On 12/16/2014 08:03 PM, Andy Bennett wrote:
> Hi,
>> Sorry, I wasn't clear on this point.  Cyrus CalDAV sends out remote
>> invites/replies in the same way that Sieve does its work.  Its done via
>> the MTA by piping the email to the local "sendmail" binary.
> Thanks for the clarification but I'm still not clear on what happens for
> users / mailboxes that the Cyrus server thinks have their INBOX hosted
> on the same server but might have routing rules in the MTA, sieve rules
> or elsewhere?
> Surely iMIP and iTIP should be entirely transparent transports and
> therefore entirely interchangeable with a native / short circuit transport?

If the user's calendars are on the same server, then the iTIP is handled 
internally per RFC6638.  The MTA never comes into play for user's hosted 
on the Cyrus server.

Technically, for users outside the Cyrus server, we first try to use 
iSchedule (iTIP over HTTP with DKIM) and then fallback to iMIP (iTIP 
over SMTP).  No currently deployed Calendaring services support 
iSchedule but I have done interop testing with Apple Calendar Server, 
Bedework, and Oracle during CalConnect events.  Cyrus uses iSchedule 
(w/o DKIM) between servers in a Murder.  The draft for iSchedule will 
eventually (we hope) be accepted by the IETF CalExt WG and progress as a 
proposed standard.

Kenneth Murchison
Principal Systems Software Engineer
Carnegie Mellon University

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