My co-worker Mark and I both regularly use our mainframe UNIX system. I've fingered him, and know that he's logged on. While I don't need to have a conversation with him, I would like to ask him if he's available to meet for a break at 2:00. From within the UNIX system, how would I do this?
1. email him
2. Send him a message using 'talk' or 'write'
3. irq (if it is setup)