I've done some more testing and I now know what is causing the problem, but not how to solve it.
We have a local Zimbra server, accessible on port 443 from the outside world, and from the lan for people in the same building. We also have wifi access points in the building and zimbra can be accessed from those also.
DHCP is configured to give an IP address to local computers and iphones and give our internal DNS server, which has a local ip entry for the Zimbra server.
When the phones are in the outside world, the DNS they see resolves the hostname of our mailserver to our external IP address.
It seems that, when on site and switching between wifi and celular networks, as the phone will go as it goes asleep; the IP it see's for mail.company.com is changing between our internal and external IP addresses.
I doubt I have a unique setup here, so I think I have something set wrong. Does anyone else run a Zimbra server, with iPhones using the exchange protocol and have reliable push while one the same lan as the server?  |