Timestamp incoming messages with the time they were originally sent, not when received.
The timestamp on an incoming message should be the time it was sent, like with e-mail. Currently the timestamp is the time received, which is useless information. A message like "see you in 2 hours" is meaningless on a device that fetches messages at long intervals, unless we know what time it was sent. You have the information in the header of the original text or email. Use that instead of replacing it on the Spot.