That's what I'd have to do anyway if the recipient was offline; why not start there? I keep a copy in my Inbox to remind me to follow up if I don't get a timely reply. Maybe I'm not using the utility correctly but it doesn't strike me as any easier to type in an IM client than an e-mail message, either sending or replying. With an e-mail, the pressure to reply immediately isn't there, there's a spell-check capability, and I can add additional people without having to see if they're on line.