Iphone Native Mail Client Syncing with Exchange 2010 Problems

Hello everyone. This is my first post, so I will do my best.

Our organization has around 14k Verizon iPhones of various models and IOS versions connected to Exchange 2010 SP3 via MobileIron. The issue is we have intermittent problems with email syncing with all of the phones. When opening the native Apple mail client, the iPhone tries to sync and sits there for several minutes before giving the error "cannot connect to the server for <mail account name>. Mail can try to repair these settings. Cancel. Repair." Clicking repair attempts to sync again and fails.

Putting phone in airplane mode and back seems to always fix the issue temporarily. The issues occurs on wireless or LTE. Using the MS Outlook client works perfectly and does not experience this issue. Unfortunately, we cannot move to the Outlook client because it is not free for enterprise use unless you are on o365.

Summary of Facts:

• Issue has been occurring for months now, but seems to be getting worse or just more people are complaining. It's hard to tell when it first started.
• When looking at the CAS logs for a user when the issue is actually occurring, there are no entries that I see for that user
• When doing a fiddler capture of the iPhone traffic when the issue is happening does not seem to give any good clues
• Capturing logs with configurator 2 when issue is occurring does give some possible clues, but maybe this is where some of you could help (
• logs attached with and without issue, same Iphone)
• Putting iPhone in airplane mode and back seems to always fix the issue temporarily
• Outlook client for Iphone has no issues
• The issues occurs on wireless or LTE
• MobileIron Logs do not show errors

ConfiguratorLogs_iphone_with_sync_pr.txt
ConfiguratorLogs_iphone_withOUT_sync.txt