I have a problem I have been banging my head against the wall on for several weeks. We have an issue where users randomly, and sometimes frequently get "cannot get mail" on their iPhones. The mail passes through two TMG servers with NLB in our DMZ, then we have two CAS\HUB servers in a NLB CAS Array, followed by two mailbox servers. I can find no error or limit messages in Exchange. I have been looking at all kinds of post and link from Google searches, but none of those seem to produce any results. So, posting things you find doing that is likely not going to be any help.
I am hoping someone knows something about ActiveSync logs. I did take a capture of a user's ActiveSync log and noticed a the time they said it happened there is a "response was pending" message. I am not sure what this means, but thought there may be someone on here who could shed some light. Most of the iPhones are running 8.3, 8.3, or 9. It seems to happen to users on Wi-Fi or the carrier's network. It also tends to happen to some people more than others.
Log Entry: 57
POST /Microsoft-Server-ActiveSync/default.eas?User=cmw1&DeviceId=7H8552HI717C1AV3VJF3PDH6UO&DeviceType=iPhone&Cmd=Ping HTTP/1.1
[Response was pending]
HTTP/1.1 200 OK
<?xml version="1.0" encoding="utf-8" ?>