HELP: How can I avoid aliases expansion in From and From: ?

[sanandre @ infomed . dia . fi . upm . es (Jose Antonio Sanandres Ledesma)]

I have a moderated list called infomed. 
The header of the messages distributed is always like this:

	From sanandre@galeno.dia.fi.upm.es Thu Apr 18 18:30 WET 1996
	Date: Thu, 18 Apr 1996 18:25:36 +0100
	From: sanandre@galeno.dia.fi.upm.es (Jose Antonio Sanandres Ledesma)
	Subject: Workshop sobre Herramientas Inteligentes en Informatica
	To: infomed@galeno.dia.fi.upm.es
	MIME-version: 1.0
	Content-transfer-encoding: 7BIT
	>From: "Original Sender"

I wonder how can I avoid that my own address appears in the fields: "From" and
"From:" instead the aliases of the list. 

I have Majordomo 1.93 with perl 5.00, on HP-UX 9.05.

	Thanks in advance.

		Jose A. Sanandres