One of our clients servers went down over a weekend and was brought back online on Monday morning . After it went back online, a slew of emails from the past 2 months that had already been sent appear to have been resent. they received numerous delivery failure notifications from these, as well as calls from confused business associates relating to others that went through successfully. We have searched Google for info on this issue with no luck. Any idea what might have caused this to occur, and what can be done to prevent it from happening again.