Logon failure - Account Currently Disabled Event 4625 | W3WP.EXE | SYSTEM

I've been receiving failed login attempts, no IP no username or any useful information
The server has Exchange 2013  and IIS installed. Mailbox Server (MBX) Information Store component is installed on this server.
The Exchange server is working well.

After thorough investigation , it is found that an application pool is causing this .We found this by executing the command "appcmd list wps" and matching the output with the process ID in the event log.It is found that app pool "MSExchangeServicesAppPool" is the culprit causing this failed login events.

Kindly let us know what could be the issue in the configuration that is causing this issue.

Below is the event


An account failed to log on.

Subject:

      Security ID:            SYSTEM

      Account Name:           SERVER-EXCHANGE$

      Account Domain:         DOMAIN

      Logon ID:         0x3E7

Logon Type:             3

Account For Which Logon Failed:

      Security ID:            NULL SID

      Account Name:          

      Account Domain:        

Failure Information:

      Failure Reason:         Account currently disabled.

      Status:                 0xC000006E

      Sub Status:       0xC0000072

Process Information:

      Caller Process ID:      0x38cc

      Caller Process Name:    C:\Windows\System32\inetsrv\w3wp.exe

Network Information:

      Workstation Name: SERVER-EXCHANGE

      Source Network Address: -

      Source Port:            -

Detailed Authentication Information:

      Logon Process:          Authz  

      Authentication Package: Kerberos

      Transited Services:     -