user accounts are constantly locked out - need

I did a trace and found that most of the lock outs seem to originate from users going to the CAS system (exchange 2010) via their mobile devices.

ex. one of many that  I see in the event viewer of the client access log. They are not all the same type but the same Event ID.

Subject:
      Security ID:            NETWORK SERVICE
      Account Name:            CASName$
      Account Domain:            mydomain
      Logon ID:            0x3e4

Logon Type:                  8

Account For Which Logon Failed:
      Security ID:            NULL SID
      Account Name:            staff@92y.org
      Account Domain:            

Failure Information:
      Failure Reason:            Unknown user name or bad password.
      Status:                  0xc000006d
      Sub Status:            0xc0000064

Process Information:
      Caller Process ID:      0xa58
      Caller Process Name:      F:\Program Files\Microsoft\Exchange Server\V14\Bin\EdgeTransport.exe

Network Information:
      Workstation Name:      CASName

I'm having a hard time understanding what some of these things mean. I've read the documents and stuff but I'm still a little unsure. Ex. below

- Logon type 8

- Call Processor Name :Windows\System32\inetsrv\w3wp.exe versus Caller Process Name:      Program Files\Microsoft\Exchange Server\V14\Bin\EdgeTransport.exe (aren't they both going to owa?)

At this point I'm trying to figure out if they locked their account first which caused their emails to fail or something on their mobile device failed which caused their accounts to be locked.