Directory Harvesting blocks emails addressed to non-existent recipients in your organization. Directory Harvesting blocks spam emails which are sent randomly to your domain.
- By default, the Block if non-existent recipients equal or exceed field is set to 1. This means that an email with one or more non-existent addresses will be blocked.
- If you find legitimate emails blocked using the default threshold setting, it is recommended to increase the threshold to at least 2. This will allow a margin of error for the senders, and should not affect the blocking of spam emails.
- If the total amount of recipients is less than the number specified, the action configured is triggered only if all the recipients do not exist, otherwise the email is not blocked as SPAM by Directory Harvesting.
- This may cause a small amount of false positives. This occurs when the sender of the email mistypes the email address. This occurrence can be lessened by configuring Directory Harvesting to block the message only if the amount of non-existent recipients is equal or greater to a pre-defined number, or if all the local email addresses in the email do not exist in your organization.
Proceed as follows to configure this threshold in the GFI MailEssentials Directory Harvesting:
- Open the GFI MailEssentials Configuration
- Expand Anti-Spam > Anti-Spam Filters > Directory Harvesting > General
- Configure the Block if non-existent recipients equal or exceed edit box
- Click Apply to save the changes.