Brightmail Spamfilter 6.0 and earlier beta releases allows remote attackers to read mail from other users by modifying the id parameter in a viewMsgDetails.do request.
https://exchange.xforce.ibmcloud.com/vulnerabilities/16609
https://euvd.enisa.europa.eu/vulnerability/EUVD-2004-0670
http://www.securityfocus.com/bid/10657