Overview

Large emails sent on a Microsoft Exchange server are not being delivered, and are instead moved to the EmailSecurity or the AntiSpam FailedMails folders.

If you have tracing enabled, the \GFI\MailEssentials\Antispam\DebugLogs\TNEF2MIME.gfi_log.txt file shows that TNEF to PFI conversion errors are logged:

2013-07-05,10:48:23,083,1,"#00001660","#00002fa8","error ","TNEF2MIME","Error 103 - aborting"
2013-07-05,10:48:23,083,1,"#00001660","#00002fa8","error ","TNEF2MIME","Exiting CTnef2MimeImpl::tnef2pfi (103) [0x80004005]"
2013-07-05,10:48:23,083,1,"#00001660","#00002fa8","error ","TNEF2MIME","Converting from TNEF to PFI...FAILED (103) [0x80004005]"

Solution

Emails that are sent on Microsoft Exchange servers are formatted in TNEF. In order for GFI MailEssentials to process such messages, they need to be converted into the MIME email format first.

The conversion requires the TNEF message size to be loaded into the memory. To protect the system from a memory overrun, the default maximum size of TNEF emails is set to 50 MB. If the email is larger, it will not be converted and treated as a failed email. The mail will then be stored in the EmailSecurity or the AntiSpam Failedmails folder.

Override the default value by increasing the maximum allocated memory to 200MB. The 200MB value was chosen as most email servers limit email size to 20MB or less. Since most compression systems will not shrink any file types to less than 10% of the original size, it was determined that using the 10x20 = 200 settings would be optimal.

In order to implement the override, please follow the steps below:

1. Navigate to Start > Run type regedit and press Enter.
2. Navigate to HKLM\SOFTWARE\Wow6432Node\GFI\MailEssentials\EmailSecurity\Config and HKLM\SOFTWARE\Wow6432Node\GFI\MailEssentials\AntiSpam\Config
3. Create a new DWORD named T2Mmaxmsgsize.
4. Right-click the new value and select Modify.
5. Enter the maximum size in bytes (decimal). The maximum value supported is 209715200.
6. Navigate to Start > Run, and type Services.msc
7. Restart the GFI MailEssentails services.

Testing

After implementing the solution above, large emails no longer fail and are delivered to the user's inbox.

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:
  1. Start > Programs > GFI MailEssentials > Troubleshooter
  2. Follow the Log Generation Wizard for collecting the required and pertinent information.
  3. 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.