If LISTSERV receives mail that has a tortured enough mail header, it will send insert new header line with the e-mail address of the local postmaster. The name field of that line will be set to "... c/o postmaster" so that people will know it wasn't really from the postmaster. If you fetch the mail file in question from the archives, there should be some indication that the original "From:" field was invalid. -jj PS - Here's an example from one of JHUVM's list archives. Nothing like a concrete example to explain something... :) ------ sample mail file follows: > print all of 1308 >>> Item number 1308, dated 92/02/02 11:40:26 -- ALL Date: Sun, 2 Feb 1992 11:40:26 EST Reply-To: Multi-byte Code Issues <[log in to unmask]> Sender: Multi-byte Code Issues <[log in to unmask]> Comments: <Parser> E: Mail origin cannot be determined. Comments: <Parser> E: Original tag was -> FROM: "xxxxxxx%nlsarch.austin.ibm.com" <xxxxxxx%nlsarch.austin.ibm.com%SUN.C From: Undetermined origin c/o Postmaster <[log in to unmask]>