I usually change mine to "Sent from my mobile" or "Sent from (xxx) xxx-xxxx" I keep a line like this for two reasons, one of which is proofreading related, but

I usually change mine to "Sent from my mobile" or "Sent from (xxx) xxx-xxxx" I keep a line like this for two reasons, one of which is proofreading related, but the more important is to let them know that the reason for my terse reply is not because I don't care or I'm upset, it's because I'm in transit (or just away from my desk).