fetchmail vs sendmail-expensive

I want local mail to be delivered immediately, including mail brought in by fetchmail. I want outgoing mail to be queued, to be delivered when cron says so. I don't want local mail from userA to userB on my local network to cause sendmail to dial up. What FEATUREs should I set up to accomplish these goals? Setting SENDMAIL_EXPENSIVE="yes" seems to queue all local mail, including that from fetchmail, but without it, local mail seems to cause a dialup. This must be a common scenario; what's the trick? TIA, Jim