The Greylist blocks legitimate emails coming from addresses with changing IPs, such as gmail.com, yahoo.com, microsoft.com, etc. Sometimes it has been observed in the dashboard log that a new sender's email is rejected a number of times before it is allowed.
The Greylist filter acquires confirmation of the legitimacy of an email by requesting an email to be resent and comparing the triplet of the sender, recipient, and sender's IP. If the sender's IP varies due to coming from a different server upon resending, the email could be blocked or delayed. More information about how the Greyfilter works can be found in the "Determining why the Greylist filter blocked or allowed a message" article.
If known, the relevant IP range could be added to the IP Exclusions list, through the settings of the filter. If the IP range is not known, and the sender is trusted, the sender's email address can be added to the Email Exclusions list, through the settings of the filter.
In case you find that the filtering is too aggressive, then the Greylist filter should not be used.
Adding either the IP range or the email address to their respective exclusion lists should allow emails to reach their destination freely.
If the issue still persists, please generate the troubleshooting logs as follows:
- Make sure that you have tracing enabled.
- Wait for at least 30 minutes to gather enough information and for the issue to be reproduced.
- Run the troubleshooter:
- Start > Programs > GFI MailEssentials > Troubleshooter
- Follow the Log Generation Wizard for collecting the required and pertinent information.
- Select New Case when completing the log generation to attach the logs to a new case that will be automatically created, or open a support ticket manually and attach the logs to that ticket, so that the Support team can investigate the problem.