Overview

The Greylist filter temporarily blocks incoming emails received from unknown senders. Legitimate mail systems typically try to send the email after a few minutes; spammers simply ignore such error messages.

This article describes how to configure the Greylist filter as well as the process to exclude certain emails that should not be delayed from the Greylist checks, for example password reset notifications.

Information

Important Notes

To enable Greylist, GFI MailEssentials must be installed on the perimeter SMTP server.
Greylist contains exclusion lists so that specific email addresses, domains, and IP addresses are not greylisted. Exclusions must be configured when:
- Emails originating from particular email addresses, domains, or IP addresses cannot be delayed
- Emails addressed to a particular local user cannot be delayed

Configuring Greylist

Log in to the MailEssentials Configuration and navigate to GFI MailEssentials > Anti-Spam > Anti-Spam Filters > Greylist.
From the General tab select/unselect Enable Greylist to enable/disable Greylist.
Select the Email Exclusions tab to specify any email addresses or domains that you do not want to greylist.
- In the edit Email Addresses/Domains area specify:
  - full email address; or
  - emails from an entire domain (e.g. trusteddomain.com)
- In addition, specify if the exclusion applies to senders (select From ) or to the local recipients (select To ).
  - Example 1: Do not greylist emails if the recipient is administrator@mydomain.com so that any emails sent to administrator@mydomain.com are never delayed.
  - Example 2: Do not greylist emails if the sender’s domain is trusteddomain.com so that emails received from domain trusteddomain.com are never delayed.
Click Add emails to add the exclusion.
- Note: To exclude whitelisted and auto-whitelisted email addresses and domains from being greylisted and delayed, select Exclude email addresses and domains specified in Whitelist and Personal Whitelist.
Select the IP Exclusions tab to specify any IP addresses to exclude from being greylisted. Click Add IPs and specify an IP to exclude.
To exclude whitelisted IP addresses from being greylisted and delayed, select Exclude IP addresses specified in Whitelist.
To log Greylist occurrences to a log file, click Actions tab and select Log rule occurrence to this file.
- Note: Log files may become very large. MailEssentials supports log rotation, where new log files are created periodically or when the log file reaches a specific size. To enable log file rotation, navigate to Anti-Spam > Anti-Spam Settings. Select Anti-spam logging tab, check Enable log file rotation and specify the rotation condition as shown below:
Click Apply to save the settings.