Chris Walker
I then looked around for another free mail reader and found Claws. If I set that up in IMAP mode, it *does* show the sent mail. Further googling showed that Claws was developed from the same code base as Sylpheed so if one program can display the sent mail, why won't the other?
Are you sure Sylpheed is looking at the same IMAP folder for sent mail? I can't find a current manual but it looks like it might be in Configuration: Edit accounts...: select account: Edit: Advanced.
Claws seems better for mailing list support BICBW
Hope that helps,