SpamAssassin Rule: RCVD_BAD_ID
Standard description: none
One of the trace fields (Received: headers) contains an unusually formatted ID parameter.
The default scores for this rule can be found in the online list of tests.
Note: matching this rule does not necessarily infer that the Received: header is invalid or non-standard, only unusual.
The format of the Received: header is defined in RFC 2821 sec 4.4 (which references atext defined in RFC 2822 ) and allows for characters beyond the ASCII alpha/digit/underscore/minus usually seen in IDs.