b2250e9c_lla_X_Mozilla_Status_explained_X_Mozilla_Status_Description
[Name] MSG_FLAG_HAS_RE [Value] 0x0010 [Description] 
Whether subject has “Re:” on the front. The folder summary uniquifies all of the strings in it, and to help this, any string which begins with “Re:” has that stripped first. This bit is then set, so that when presenting the message, we know to put it back (since the “Re:” is not itself stored in the file).
Christian Eyrich - Mozilla X-Mozilla-Status explained
Description