Neil, Thanks for alerting me to the fact that Simon was quoting a Knowledge Base article - the article's not on November's Technet despite the website version being last reviewed in July! (If we had more reliable internet access I'd've been more inclined to check the web first: I have been warned before that it's more up-to-date - but over 3 months!!).
I forgot one important detail: we're using GroupShield 4.0.4 - reading the full article I've found what will hopefully be the resolution. Many thanks, Karen List Charter and FAQ at: http://www.sunbelt-software.com/exchange_list_charter.htm
