MailEssentials 21.6 was released in January 2020 and has caused issues with mail flow after an upgrade. This is caused by a few incorrectly placed DLL files, causing the system to fail when processing mail due to a known issue when directly installing on an existing version without requisite patches.
This article provides a background on the root cause as well as a solution to the problem.
Installing the latest release of MailEssentials results in interrupted mail flow when MailEssentials is enabled as described in Enabling or Disabling GFI MailEssentials Processing.
GFI Development published a new 21.6 release with the upgrade failures resolved. Downloading a fresh copy of the installer and installing it with the latest re-release will resolve the issue.
After a failed upgrade, re-installing the application with the fixed 21.6 installer will put the .dll files in place and allow for normal mail flow. Before completing the process below, it is recommended to back up the configuration settings. Upgrading usually keeps the existing configuration in place. However, it is always good practice to have a backup of your MailEssentials configuration.
Go to Control Panel.
Locate MailEssentials and select Uninstall.
After completing the uninstall process, locate the previously downloaded MailEssentials 21.6 installer.
Right-click on the installer and select Run as Administrator.
Verify that the installer is pointed to the same install location as the previous installation and that the previous settings should be used. The backup will not be needed and can then be deleted once you have confirmed that the settings are the same.Note: If any of the settings are missing, refer to the Restoring a Manual Backup of MailEssentials article to restore the settings.