You're correct that Lamson provides tools for processing emails, but it doesn't include a mechanism for feeding it emails from IMAP servers. Switchboard actually complements Lamson -- Switchboard could manage IMAP connections, collect incoming emails, and feed those emails to Lamson. You'd be able to use Lamson in front of Gmail/Yahoo/etc

I'm not super familiar with Apache James, but it appears to be a mail server with pluggable components. Switchboard fits in as a layer between any mail server that supports IMAP, and its version of pluggable components [processes connection over the interface].

Thanks, this really helps us see where the documentation needs to be improved :)