Nicole,
That's exactly what we're trying to verify...A device not on the local network (e.g. smartphone remotely accessing mail). We have one iPhone user that keeps getting locked out of his domain account. We've tracked it down to either a virus, Windows backup login error or a Smartphone). No viruses found and we've disabled the windows backup service so we're back to thinking its his Smarphone. Apple support forums show/acknoledge this issue, but comes short of admittion or a solution.
Thank you very much for your input. Its been very helpful.
Steve