Multi-Recipient E-mail Messages: Privacy Issues and Possible Solutions

Abstract

Chain and multi-recipient e-mails pose significant security and privacy threats such as phishing and the spread of Trojan horses. They also increase the chances of receiving spam e-mails. E-mails sent to multiple recipients at a time result in unwanted exposure of e-mail address to multiple recipients. The recipients of chain e-mails may include spammers or e-mail addresses of users whose e-mail account or device may have been compromised, thereby, exposing all email addresses to spammers. Forwarding or sending a multirecipient e-mail in a chain further increases the exposure of email addresses to spammers. This paper discusses chain emails, multi-recipient e-mails and crucial security and privacy threats they pose to legitimate e-mail user. It also discusses various possible mechanisms to mitigate these threats and investigates their effectiveness. This study proposes a novel technique to counter these security risks by enhancing the default behaviour of e-mail client, SMPT server and SMTP protocol. The proposed technique has been implemented in the Java programming language which showed promising results against unnecessary exposure of multiple e-mail addresses while sending an e-mail to multiple recipients.