So far, I have been using pan. However, it tends to become painfully slow when the groups contain more than 30.000 messages; exponentially slow. On the other hand, I don't want to re-ask old questions, and prefer the archive of gmane.org, which as of now contains almost 100.000 posts. With numbers like this, to search for a keyword in the subject or an author's name, it can take literally minutes to sort through the posts in order to come up with the result.
I have also briefly looked at Thunderbird and Sylpheed, but both seem to suffer from a similar problem. Neither seems to implement advanced search strategies like hashing and stuff. All seem to do pure text / string searches. ('seem' == I didn't look at the code.) Now I'd really appreciate your recommendation for a method or apparatus to handle groups with large numbers of messages in a suitable and reasonably fast manner. Thanks in advance, Uwe