IMF does not scan messages larger than 3 Mb

by Bharat Suneja

Microsoft has just released a knowledgebase article – KB 907691 – documenting the inability of its Intelligent Message Filter (IMF) – the anti-spam filter that was earlier offered as a free add-on for Exchange Server 2003 – to scan messages over 3 Mb. in size.

When IMF encounters a message that is larger than 3 Mb., it logs the following event in the Application Event Log:

Event ID: 7515
Category: SMTP Protocol
Source: MSExchangeTransport
Type: Error Message : An error occurred while Microsoft Exchange Intelligent Message Filter attempted to filter a message with ID <ID_Number>, Priority_Number From smtp:E-mail_ID and Subject Subject_Text. This message will not be filtered. The error code is 0x800710f0.

(In some of my tests IMF has behaved differently when scanning these large (over 3 Mb.) messages with and without attachments. I haven’t been able to complete testing to come to any conclusion because of lack of time – will update this post if I find something – Bharat)

IMF became part of Exchange Server 2003 when Microsoft included it in Exchange Server 2003 Service Pack 2. The inability to scan messages over 3 Mb. in size is common to both IMF v1 and the new version 2 included with SP2.

The article states this is by design – typical spam messages are not as large, and it costs more to send such spam.

It’ll be interesting to find out what Exchange administrators think about this!

{ 1 comment… read it below or add one }

Anonymous August 23, 2006 at 9:15 am

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