Mail Quits unexpectedly every time it opens I have a serious problem with the Mail application. It just won't open. I've seen some 'remedies' for example, resetting rules and settings, but this can't be done if the app doesn't even open. 

Process:               Mail [7832]
Path:                  /Applications/Mail.app/Contents/MacOS/Mail
Identifier:            com.apple.mail
Version:               9.2 (3112)
Build Info:            Mail-3112000000000000~7
Code Type:             X86-64 (Native)
Parent Process:        ??? [1]
Responsible:           Mail [7832]
User ID:               501

Date/Time:             2016-03-27 13:50:44.435 +0800
OS Version:            Mac OS X 10.11.3 (15D21)
Report Version:        11

Time Awake Since Boot: 52000 seconds
Time Since Wake:       11000 seconds

System Integrity Protection: enabled

Crashed Thread:        27  Dispatch queue: Task Manager Serialization Queue :: NSOperation 0x7fc5c84d2430 (QOS: LEGACY)

Exception Type:        EXC_CRASH (SIGABRT)
Exception Codes:       0x0000000000000000, 0x0000000000000000
Exception Note:        EXC_CORPSE_NOTIFY

Application Specific Information:
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Attempting to perform a synchronous operation while on the serialization queue'
abort() called
terminating with uncaught exception of type NSException


Please help! Mail is a reasonably important part of doing business 
(Full error log here).


  This is different from Mail.app crashes constantly, even after deleting mail profile and cache,
  because users are able to open
  the app to commence remediation activities there. As stated, I had tried
  this but each time the the app opens it crashes immediately. The
  resolution in the other thread is not possible to implement in this
  case.
I had similar problem. The crash report was:

Exception Type:        EXC_CRASH (SIGABRT)
Exception Codes:       0x0000000000000000, 0x0000000000000000
Exception Note:        EXC_CORPSE_NOTIFY 


If your crash note is  EXC_CORPSE_NOTIFY, Then deleting all your accounts and re-adding them will solve your problem.