Content Filtering Component of Symantec Mail Security for Domino will not work on very small in-line attachments
Last Updated October 22, 2013
You configured Symantec Mail Security to filter file attachments (for example, executable attachments with a .EXE extension). Sometimes, very small attachments that match the content filtering rule or rules are not filtered.
Symptoms Attachments within messages are not seen by content filtering rules and appear to slip by the content filtering (CF) product component.
In-line attachments smaller than 42 KB are seen as inline or embedded to the message body and not as attachments. Therefore inline mime attachments less than 42KB will not be converted and copied into the $File field. Internal to our product we hard coded a feature so that it would be enabled always which allows are product to scan all details of the message body. This allows the product to scan inline attachments for viruses but this process does not until after CF rules have been ran and so this can not resolve the content filter rules issue. There are several methods of which can be coded but are very complex.
This problem occurs when the attachment is 42 kilobytes or smaller and the email arrives with the disposition-type set to "inline".
To work around this problem, you can configure Domino to convert all in-line files to file attachments, regardless of their size. To configure Domino in this manner, add the following line to your Notes.ini file:
Note: This configuration causes all small attachments, such as pictures, to become attachments instead of getting displayed as part of the message body.
References For more information about the MIMEForceAttachments=1 parameter, read the following IBM Technote:
Technical Information Lotus Domino does not convert in-line files that are smaller than 42 kilobytes to file attachments. These small files remain part of the email body. The Content Filtering component for Symantec Mail Security cannot detect and filter against these inline attachments.
Imported Document ID: TECH85322
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