No new emails were delivered for my Networknet.nl domain. Second configured MX record received new emails for my personal email address. I logged on the Exchange 2007 server but at first glance I could not see any issues. I opened Internet Explorer and browsed to http://centralops.net/co/EmailDossier.aspx.

Email Dossier from Centralops.net

Allows you to validate and investigate email addresses.

SMTP session

[Contacting mx1.networknet.nl ...]
[Connected]
220 w2k8.Networknet.nl Microsoft ESMTP MAIL Service ready at Wed, 30 Dec 2009 17:41:56 +0100
EHLO hexillion.com
250-w2k8.Networknet.nl Hello [70.84.211.98]
250-SIZE 10485760
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-STARTTLS
250-AUTH
250-8BITMIME
250-BINARYMIME
250 CHUNKING
MAIL FROM:<[email protected]>
452 4.3.1 Insufficient system resources
MAIL FROM:<>
452 4.3.1 Insufficient system resources
[Unfavorable reply code, cannot continue]
RSET
[Contacting mx2.networknet.nl ...]
[Connected]

Message 452 4.3.1 Insufficient system resources was shown during the SMTP session. I went back to the Exchange 2007 server and saw that I only had 700mb free on my C:\ volume. I opened Server Manager and checked Applications eventviewer and than I filtered for Error events. The result showed following error evenid 15006:

Log Name: Application

Source: MSExchangeTransport

Date: 12/30/2009 5:50:22 PM

Event ID: 15006

Task Category: ResourceManager

Level: Error

Keywords: Classic

User: N/A

Computer:w2k8

Description:

The Microsoft Exchange Transport service is rejecting message submissions because the available disk space has dropped below the configured threshold.

Resource utilization of the following resources exceed the normal level:

Queue database and disk space ("C:\Program Files\Microsoft\Exchange Server\TransportRoles\data\Queue\mail.que") = 97% [Medium] [Normal=94% Medium=96% High=98%]

Queue database logging disk space ("C:\Program Files\Microsoft\Exchange Server\TransportRoles\data\Queue\") = 97% [Medium] [Normal=94% Medium=96% High=98%]

No components were disabled because of back pressure.

The following resources are in the normal state:

Version buckets = 0 [Normal] [Normal=80 Medium=120 High=200]

Private bytes = 0% [Normal] [Normal=71% Medium=73% High=75%]

Physical memory load = 81% [limit is 94% before message dehydration occurs.]

So my free diskspace was low and the Microsoft Exchange Transport service stopped. I run the Windows Backup utility to backup my Exchange 2007 server and truncate the exchange log. This Exchange 2007 environment is hosted in a lab and no scheduled backup jobs are yet set. Something I should do quickly.