For my partner and I anyway. I think the real key to this rests in Merlin’s post where he talks about setting agreed-upon standards for team.

My team uses Gmail and we seem to have a kind of natural escalation where we will first use the embedded chat feature to IM each other items or requests of an ephemeral, momentary nature.

If we’re having an IM conversation and it gets too complex after a couple minutes we’ll either call on the phone, or set an appointment to talk it through on the phone.

If the request is something not super time critical or if the person is not online, we usually defer to email.

For group conversations and mailing lists, I filter them out of my inbox to a ‘mailing lists’ label and then skim through it each day, opening and reading the ones I’m interested in.