Standard and Professional Editions of MailEnable store details in TAB delimited files. Because this file can be updated by multiple applications (e.g.: Administration Program, web administration, Control Panels, etc), MailEnable implements its own means of locking files to ensure data integrity. Hence, when updates to these files are required the system performs the following actions:

1. Creates a BLK file to notify other applications/agents that a file needs to be updated.
2. Once all file access has been blocked, the required changes are recorded to a TMP file. 
3. This file is then renamed to a .TAB file. 
4. Finally, the .BLK file is removed by the caller. Each of these operations will be re-tried for up to a minute if they cannot be executed. Hence if a calling process has crashed or failed when it was attempting to update the file, the .BLK file is left resident. This will obviously cause problems with Administration. To resolve this, search under the Mail Enable\Config directory for .BLK files and remove them. It is also important to identify any applications that may have the file locked. For example, if one of the .TAB files is opened in Excel, MailEnable will be unable to update it. Also, ensure that you have authenticated with an account that has full access to the C:\Program Files\Mail Enable\Config directory and its sub directories, and that the all the files under this directory are not Read Only protected (i.e. ensure that MailEnable can update the TAB files under the CONFIG directory).