When end users attempt to log in to the Messaging Gateway Control Center, the attempt results in an Application Error and the end user cannot log in.
Login attempts result in the following screen, preventing login:
The Control Center BrightmailLog.log file will contain errors similar to:
Mar 06 2018 11:32:49 [http-bio-443-exec-4] [ExceptionHandler] ERROR - java.util.regex.PatternSyntaxException: Unclosed counted closure near index 7 test{12E4.EN_US}@domain\.tld
While there could be other reasons cause an application error on login, this article is specific to a problematic entry in the Policy Group Members configuration.
To correct this issue, you will need to remove problematic email address(es) from the policy group membership list(s).