I have an end-user who is having problems synchronizing Exchange mail on his iPhone and iPad on two occasions now.  First time was on 3/26 at noon and started working again on its own the following day.   It is now happening again on 4/11 at 9:30 a.m.  We are on Office 365 (P1) Plan.  Devices are on iOS 5.1.

I have tried various steps to no avail.  Please below.

1.)  Verified account credentials are correct

2.)  Verified account is 'Unlock'

3.)  Verified Exchange ActiveSync is Enabled

4.) On both iPhone/iPad (steps from Apple communities posted on 3/25/2012)

- Go to settings
- General
- Reset
- Reset Networking Settings
- Settings
- General
- Network
- Switch the Wi-Fi On
- Enter your Credentials (check you internet connection by accessing any webpage, i.e. google.com)
- General
- Setup your Microsoft Exchange account
- Restart your phone
- Test sending and receiving

5.)  Created "Configuration Profile" http://maketecheasier.com/connect-exchange-account-from-iphone/2011/02/14

6.) Deleted accounts from iPhone/iPad

- Logged on to Office 365, reprovisioned end-user's account 

- Waited 1 hour

- Recreated Microsoft Exchange account on both devices and received 'unable to verify account information'

- Logged on to OWA as end-user

- Checked on settings and received the following error when clicked on refresh icon

Cannot open mailbox /o=ExchangeLabs/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=CH1PRD0510MB355/cn=Microsoft System Attendant.

Hello Tia,

So just that I understand this correctly, please confirm that the accounts do work on the devices, but only work intermittently. I will check with our mobile team to see if they may have some more insight into this.

I look forward to hearing from you.

Brandon Kempma
 Office 365 Technical Support.