When using connectors with authentication through Active Directory such as the Exchange connector, some users are encountering login failures.
The source machine (ShareScan) and target server (Domain Controller, etc) are not using the same level of authentication. This can result in Audit Failures in the eventlog (unknown user name or bad password) that correspond to the account being used.
The Local Security Policy on the ShareScan host machine may need to be set to allow NTLM responses. Review the following information from Microsoft.
Network security: LAN Manager authentication level
Quick Reference: Troubleshooting Netlogon Error Codes