So I just received this email again:
From: Reviewers Conference <firstname.lastname@example.org>
Subject: Thank you for your commitment to support us as a WMSCI 2007's
Date: 16 Aug 2007 15:09:36 -0400
Dear Didier Verna:
On behalf of the Organizing Committee of The 11th World Multi-Conference on Systemics, Cybernetics and Informatics (WMSCI 2007), I would like to thank you very much for your commitment to support us as a WMSCI 2007's reviewer.
You are one of our few cases who did not receive from us a notice for their possible support in the conference reviewing process. The causes were the lack of submissions in your area and/or a bug we found in the program by means of which a random selection of the reviewers were made in the last conference. We are fixing this bug so it will not happen again in the future.
We would like to inform you that we maintained your name among the reviewers of the WMSCI 2008 conference. If for any reason you will not be able to support us, as a reviewer of the next conference, we will highly appreciate your information about it by means of a reply to this email.
We really appreciate your co-operation, and we hope we will have your support again for WMSCI 2008.
Prof. Nagib Callaos
WMSCI 2007 General Chair
So you know, the bug must be damn hard to fix because I'm receiving this email every year since at least 2003... But yeah, I'm gonna support them again, by not reporting this as spam, as I should.