Answer

PROBLEM

No emails are being detected as spam by the GFI MailEssentials greylist anti-spam filter.

ENVIRONMENT

• GFI MailEssentials
• All supported environments

SOLUTION

Greylist is disabled
 
Perform the procedure described below to ensure that the GFI MailEssentials greylist feature is enabled:

1. Open the GFI MailEssentials Configuration
2. Proceed to Anti-Spam > Anti-Spam Filters
3. Right click on the Greylist node and select Properties
4. Under the General tab, ensure that Enable Greylist is checked 

Incorrect IP or email exclusion

Ensure that there are no incorrect exclusions configured in the GFI MailEssentials configuration. Perform the following procedure to review the Greylist exclusions:

1. Open the GFI MailEssentials Configuration
2. Proceed to "Anti-Spam" > "Anti-Spam Filters" > "Greylist"
3. Click on the "Email exclusions" tab. Ensure that you have not included your own domain or any generic top level domains such as *@*.com
4. Click on the "IP exclusions" tab. Ensure that you have not excluded the IP address of your own mail server

Corrupt Greylist database
 
The GFI MailEssentials Greylist feature will fail to process emails if the greylist database is corrupt. The following procedure will explain how to run an integrity check on the GFI MailEssentials greylist database to ensure it is not corrupt: 

1. Stop the GFI MailEssentials services
   • Note: Stopping the services will stop anti-spam filtering
2. Create a backup of the greylist database
   • by default <GFI\MailEssentials\Antispam\Data\greylisting.db>
3. From  a command prompt, change the path to the folder of the greylist database
4. To repair the database, run the command esentutl /p <database name>
   • Note: The <databasename> is the name of the Greylist database
   • Example: esentutl /p greylist.db
5. Click OK to start the integrity check
6. Once completed, start the GFI MailEssentials services

Corrupt transaction log files

The GFI MailEssentials Greylist feature will fail to initialize if the transaction log files are corrupted. This can for example occur if the GFI MailEssentials Scan Engine would crash whilst modifying the transaction logs. The following procedure will explain how to reset the transaction logs to fix this problem:

1. Stop the GFI MailEssentials services
   • NOTE: Stopping the services will stop anti-spam filtering
2. Create a backup of the greylist log files folder
   • by default <GFI\MailEssentials\Antispam\Data\GreylistLogs>
3. Delete the contents of the GreylistLogs folder
4. Once completed, start the GFI MailEssentials services

CAUSE

This issue may be caused for several reasons (mentioned above). Please refer to the solution section for more information.