Low Disk Space Handling in MailMarshal SMTP

This article applies to:

• Trustwave MailMarshal (SEG) 6.3 and above

Question:

• How does MailMarshal SMTP handle low disk space on processing servers?

Information:

MailMarshal SMTP checks for available free space on the partition(s) where the working directories reside.

In version 6.3 and above the disk space checking operates as follows:

• When free space drops below the delay mark, the Receiver throttles email acceptance by delaying before accepting each message (a minimum of 10 seconds by default).
  • A delay email notice is sent to the administrator the first time a message is delayed, and periodically thereafter (by default, after 24 hours; the notice is triggered when a message is delayed).
• When free space drops below the low mark, the Receiver stops accepting email. Each message is refused with a SMTP response indicating insufficient disk space.
  • A single email notice is sent to the administrator when the Receiver stops accepting email. (To avoid multiple notices when the free space is fluctuating around the low mark, no further email notice will be sent until the free space rises above the delay mark and then falls again.)
• These events are logged in the Windows event log and the MailMarshal Receiver log.
• The default values for delay mark are:
  • Software (6.4.0): 1.5GB
  • Software (6.4.1 and above): 1GB
• The default values for low mark are:
  • Software (6.4.0): 1GB
  • Software (6.4.1 and above): 512 MB

To configure these settings, you can enter a number of values in the Registry or MailMarshal (SEG) 10 Advanced Settings.

1. On the Array Manager, edit the Registry (10.X: use Advanced Settings in the Management Console)
2. Navigate to the SEG Receiver key:
   • In version 8.X: HKEY_LOCAL_MACHINE\SOFTWARE\Trustwave\Secure Email Gateway\Default\Receiver
   • 10.X: value names have the prefix Receiver. (Receiver dot).
   • For full details of the location for each product version, see article Q10832.
3. Enter one or more of the following DWORD values (add the DWORD entries if they are not present):
   • DelayDiskMark: If free disk space falls below this value, the Receiver begins to throttle acceptance Enter a value in Megabytes. 
     • DelayMinThreshold: Minimum seconds delay per message when throttling (default: 10).
     • NotifyInterval: Time between notification emails to administrator, in seconds (default: 86400 seconds [24 hours]).
   • LowDiskMark: If free disk space falls below this value, the Receiver stops accepting email. Enter a value in Megabytes. 
4. Commit configuration changes
5. Restart the Receiver service on each email processing server .

Warning: Using the Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Trustwave cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Make sure that you back up your Registry prior to making any changes.

Disabling the Disk Check:

In version 6.4.1 through 6.4.7, there is a known issue with low disk checking that can cause false triggering.

If you are experiencing problems with this feature and you cannot upgrade immediately, you can disable this check. You will still receive the notifications but the Receiver will not slow down or reject messages during this time. Remember to re-enable the check once you upgrade.

To disable the disk check:

Under HKEY_LOCAL_MACHINE\SOFTWARE\NetIQ\MailMarshal\Default\Receiver

Add the following DWORD entries if they are not present, and set the value of both to 0:

• DelayDiskMark 
• LowDiskMark

To apply these values, see the instructions above.

Be aware that if the server actually runs out of disk space, messages being processed could be lost.

Notes:

• All values are decimal.
• In earlier versions of MailMarshal SMTP, the required free space is 100MB.