How can I browse old mails in an IMAP folder?

Both the build-in mail client (Android 2.1) and K-9 mail, display the most recent n messages received during the last m days, where m and n are configuration items. Messages older than m days are invisible. It's certainly sensible to hide old mail my by default, but how cannot I lookup an old message in INBOX or another folder? Even if the INBOX folder is huge, retrieving all headers should be an option.