When i send an appointement by Thunderbird 3.4.1 (with lightning 3.3.2 and sogo connector 31.0.1) or by webmail of Zentyal 4.0 (with Openchange 4.0.6) or by Outlook 2010/2013 to an other account of my mail domain, I see the .ics meeting on iPhone always displayed at 1-1-2001 from 1.00 to 1.00.
From the phone, when i accept (or deny or tentative) the event, it generates correctly mail reply and also i can see correctly the appointment in the phone calendar (and also in the other mail client), but the invitation of the first mail remains always with wrong date and time.