Here is the list of macros, witch I found at http://weblogs.asp.net/jan/archive/2004/02/20/77152.aspx.
%MessageID% Unique identifier of the message in BizTalk Server (GUID). The value is taken directly from message context property BTS.MessageID %datetime_bts2000% UTC date time in format YYYYMMDDhhmmsss, where sss means seconds and milliseconds (e.g. 199707121035234 means 1997/07/12, 10:35:23 and 400 milliseconds) %datetime% UTC date time in format YYYY-MM-DDThhmmss (e.g. 1997-07-12T103508) %datetime.tz% Local date time + time zone from GMT in format YYYY-MM-DDThhmmssTZD, (e.g. 1997-07-12T103508+800) %time% UTC time in format hhmmss %time.tz% Local time + time zone from GMT in format hhmmssTZD (e.g. 124525+530) %SourceFileName% (it's case sensitive) name of the file that was received by the receive port.