To clear mail queue from MailEnable - Windows server one needs to follow the below mentioned steps:
1. Log in to your Windows Server as an "administrator"
2. Expand the MailEnable Management directory.
3. Expand servers.
4. Expand local host and select Connectors.
5. From one of the Connectors, select Queues.
6. Select the Inbound or Outbound queue.
7. To clear the queue, remove the files.
Note: If MailEnable freezes when populating the mail queue, one may have too many files and must remove the files via command line.