2.2.4 Extended Rules Message Syntax
Using standard rules for message processing, as specified in section 2.2.1, section 2.2.2, and section 2.2.3, has one major limitation as a consequence of using the ROP layer as the underlying transport: there is an inherent size limitation of 32 kilobytes per ROP package. To work around this limitation, extended rules were created. Extended rules are built using the Message and Attachment Protocol as specified in [MS-OXCMSG], so that messages can be spread over multiple ROPs to avoid the size limitation. An extended rule is defined as an FAI message in a folder that has the value of the PidTagMessageClass property ([MS-OXCMSG] section 18.104.22.168) set to "IPM.ExtendedRule.Message". This FAI message also has a set of rule-related properties set on it, as specified in the following subsections. To create, modify, or delete an extended rule, the application is required to create, modify, or delete the underlying FAI message.
Extended rules use a different set of properties than the RopModifyRules ROP ([MS-OXCROPS] section 22.214.171.124). However, these properties map to properties for RopModifyRules; and except where noted, their formats are identical and the same syntactic restrictions (2) and semantic meanings of values apply as the respective property defined in section 126.96.36.199.1.