Why don newsgroup filters work?
This is usually the same reason as for question 4.1. However, there is a work-around and that is to use the XREF header instead. The XREF header contains the list of newsgroups that the mesage was stored in on your news server. This may be slightly shorter than the original newsgroups line if your server doesn’t carry all the groups that the message was posted to. Also, the format of XREF is different in that it also contains the number of the article in each group, so be sure to use wildcards in between newsgroup names.
