PMDF System Manager's Guide

The disclaimer channel takes great pains to make sure that it does not modify messages in such a way that it compromises the integrity of the message. For example, it does not make any modifications to the bodies of any signed messages (which would invalidate the signature), or reports such as NOTARY messages or NDNs (Non-Delivery Notices).

For simple (non-multipart) messages, the disclaimer channel only adds disclaimers to the bodies of text/plain and text/html messages. Messages of any other non-multipart content-type are not modified.

For multipart messages, the disclaimer channel only looks at the following content-types:

multipart/alternative
multipart/mixed
multipart/related
multipart/parallel

Within the multipart message, only parts that are text/plain or text/html are modified. Only the first part of each type is modified.

For each text/plain or text/html part or entire message, additional checks are made to make sure it is a part or message that should be modified. For example, this ensures that PMDF does not modify attachments, such as files or images or binary executables.

The disclaimer channel also makes sure that it does not add the disclaimers twice by marking each message that it modifies with a X-Disclaim-Comment header.